diff --git a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/findUpcomingCalendarEvent.test.ts b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/findUpcomingCalendarEvent.test.ts
index d6d3d556f..dce86cc71 100644
--- a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/findUpcomingCalendarEvent.test.ts
+++ b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/findUpcomingCalendarEvent.test.ts
@@ -5,32 +5,32 @@ import { CalendarEvent } from '@/activities/calendar/types/CalendarEvent';
 import { findUpcomingCalendarEvent } from '../findUpcomingCalendarEvent';
 
 const pastEvent: Pick<CalendarEvent, 'startsAt' | 'endsAt' | 'isFullDay'> = {
-  startsAt: subHours(new Date(), 2),
-  endsAt: subHours(new Date(), 1),
+  startsAt: subHours(new Date(), 2).toISOString(),
+  endsAt: subHours(new Date(), 1).toISOString(),
   isFullDay: false,
 };
 const fullDayPastEvent: Pick<CalendarEvent, 'startsAt' | 'isFullDay'> = {
-  startsAt: subDays(new Date(), 1),
+  startsAt: subDays(new Date(), 1).toISOString(),
   isFullDay: true,
 };
 
 const currentEvent: Pick<CalendarEvent, 'startsAt' | 'endsAt' | 'isFullDay'> = {
-  startsAt: addHours(new Date(), 1),
-  endsAt: addHours(new Date(), 2),
+  startsAt: addHours(new Date(), 1).toISOString(),
+  endsAt: addHours(new Date(), 2).toISOString(),
   isFullDay: false,
 };
 const currentFullDayEvent: Pick<CalendarEvent, 'startsAt' | 'isFullDay'> = {
-  startsAt: startOfDay(new Date()),
+  startsAt: startOfDay(new Date()).toISOString(),
   isFullDay: true,
 };
 
 const futureEvent: Pick<CalendarEvent, 'startsAt' | 'endsAt' | 'isFullDay'> = {
-  startsAt: addDays(new Date(), 1),
-  endsAt: addDays(new Date(), 2),
+  startsAt: addDays(new Date(), 1).toISOString(),
+  endsAt: addDays(new Date(), 2).toISOString(),
   isFullDay: false,
 };
 const fullDayFutureEvent: Pick<CalendarEvent, 'startsAt' | 'isFullDay'> = {
-  startsAt: addDays(new Date(), 2),
+  startsAt: addDays(new Date(), 2).toISOString(),
   isFullDay: false,
 };
 
diff --git a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventEnded.test.ts b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventEnded.test.ts
index 0efcf75e4..7519fb7e0 100644
--- a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventEnded.test.ts
+++ b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventEnded.test.ts
@@ -6,8 +6,8 @@ describe('hasCalendarEventEnded', () => {
   describe('Event with end date', () => {
     it('returns true for an event with a past end date', () => {
       // Given
-      const startsAt = subHours(new Date(), 2);
-      const endsAt = subHours(new Date(), 1);
+      const startsAt = subHours(new Date(), 2).toISOString();
+      const endsAt = subHours(new Date(), 1).toISOString();
       const isFullDay = false;
 
       // When
@@ -21,27 +21,10 @@ describe('hasCalendarEventEnded', () => {
       expect(result).toBe(true);
     });
 
-    it('returns false for an event if end date is now', () => {
-      // Given
-      const startsAt = subHours(new Date(), 1);
-      const endsAt = new Date();
-      const isFullDay = false;
-
-      // When
-      const result = hasCalendarEventEnded({
-        startsAt,
-        endsAt,
-        isFullDay,
-      });
-
-      // Then
-      expect(result).toBe(false);
-    });
-
     it('returns false for an event with a future end date', () => {
       // Given
-      const startsAt = new Date();
-      const endsAt = addHours(new Date(), 1);
+      const startsAt = new Date().toISOString();
+      const endsAt = addHours(new Date(), 1).toISOString();
       const isFullDay = false;
 
       // When
@@ -59,7 +42,7 @@ describe('hasCalendarEventEnded', () => {
   describe('Full day event', () => {
     it('returns true for a past full day event', () => {
       // Given
-      const startsAt = subDays(new Date(), 1);
+      const startsAt = subDays(new Date(), 1).toISOString();
       const isFullDay = true;
 
       // When
@@ -74,7 +57,7 @@ describe('hasCalendarEventEnded', () => {
 
     it('returns false for a future full day event', () => {
       // Given
-      const startsAt = addDays(new Date(), 1);
+      const startsAt = addDays(new Date(), 1).toISOString();
       const isFullDay = true;
 
       // When
@@ -89,7 +72,7 @@ describe('hasCalendarEventEnded', () => {
 
     it('returns false if the full day event is today', () => {
       // Given
-      const startsAt = new Date();
+      const startsAt = new Date().toISOString();
       const isFullDay = true;
 
       // When
diff --git a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventStarted.test.ts b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventStarted.test.ts
index 2dcc38876..5e0ddaea4 100644
--- a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventStarted.test.ts
+++ b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/hasCalendarEventStarted.test.ts
@@ -5,7 +5,7 @@ import { hasCalendarEventStarted } from '../hasCalendarEventStarted';
 describe('hasCalendarEventStarted', () => {
   it('returns true for an event with a past start date', () => {
     // Given
-    const startsAt = subHours(new Date(), 2);
+    const startsAt = subHours(new Date(), 2).toISOString();
 
     // When
     const result = hasCalendarEventStarted({ startsAt });
@@ -16,7 +16,7 @@ describe('hasCalendarEventStarted', () => {
 
   it('returns false for an event if start date is now', () => {
     // Given
-    const startsAt = new Date();
+    const startsAt = new Date().toISOString();
 
     // When
     const result = hasCalendarEventStarted({ startsAt });
@@ -27,7 +27,7 @@ describe('hasCalendarEventStarted', () => {
 
   it('returns false for an event with a future start date', () => {
     // Given
-    const startsAt = addHours(new Date(), 1);
+    const startsAt = addHours(new Date(), 1).toISOString();
 
     // When
     const result = hasCalendarEventStarted({ startsAt });
diff --git a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/sortCalendarEvents.test.ts b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/sortCalendarEvents.test.ts
index 2e0208d6e..dc1a42a9c 100644
--- a/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/sortCalendarEvents.test.ts
+++ b/packages/twenty-front/src/modules/activities/calendar/utils/__tests__/sortCalendarEvents.test.ts
@@ -14,13 +14,13 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts non-intersecting events by ascending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusOneHour,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusOneHour.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusTwoHours,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusTwoHours.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -36,13 +36,13 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts intersecting events by start date ascending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusTwoHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusTwoHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusOneHour.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -58,13 +58,13 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts events with same start date by end date ascending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusTwoHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusTwoHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDate,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -80,13 +80,13 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts events with same end date by start date ascending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusOneHour.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -102,11 +102,11 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts events without end date by start date ascending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
+      startsAt: someDatePlusOneHour.toISOString(),
       isFullDay: true,
     };
 
@@ -122,11 +122,11 @@ describe('sortCalendarEventsAsc', () => {
   it('returns 0 for full day events with the same start date', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
     const eventB = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
 
@@ -142,12 +142,12 @@ describe('sortCalendarEventsAsc', () => {
   it('sorts the full day event last for two events with the same start date if one is full day', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusOneHour,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusOneHour.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
 
@@ -165,13 +165,13 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts non-intersecting events by descending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusOneHour,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusOneHour.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusTwoHours,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusTwoHours.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -187,13 +187,13 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts intersecting events by start date descending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusTwoHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusTwoHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusOneHour.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -209,13 +209,13 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts events with same start date by end date descending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusTwoHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusTwoHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDate,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -231,13 +231,13 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts events with same end date by start date descending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
-      endsAt: someDatePlusThreeHours,
+      startsAt: someDatePlusOneHour.toISOString(),
+      endsAt: someDatePlusThreeHours.toISOString(),
       isFullDay: false,
     };
 
@@ -253,11 +253,11 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts events without end date by start date descending order', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
     const eventB = {
-      startsAt: someDatePlusOneHour,
+      startsAt: someDatePlusOneHour.toISOString(),
       isFullDay: true,
     };
 
@@ -273,11 +273,11 @@ describe('sortCalendarEventsDesc', () => {
   it('returns 0 for full day events with the same start date', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
     const eventB = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };
 
@@ -293,12 +293,12 @@ describe('sortCalendarEventsDesc', () => {
   it('sorts the full day event first for two events with the same start date if one is full day', () => {
     // Given
     const eventA = {
-      startsAt: someDate,
-      endsAt: someDatePlusOneHour,
+      startsAt: someDate.toISOString(),
+      endsAt: someDatePlusOneHour.toISOString(),
       isFullDay: false,
     };
     const eventB = {
-      startsAt: someDate,
+      startsAt: someDate.toISOString(),
       isFullDay: true,
     };