Angular unit test for Angular Material DatePicker failing, can't understand why

I've got these 2 Unit tests for the Angular Material DatePicker in Angular. I can't understand why the result I get is 1 vs. expected 31...

describe('startTimeChange', () => {
test('should emit updated input start date range with time', () => {
component.ngOnInit();
jest.spyOn(component, 'dateRangeChanged');

// any = MatDatepickerInputEvent<Date>
const updatedDateTime: any = {
value: new DateRange<moment.Moment>(moment(), component.dateRange.end)
}

component.startTimeChange(updatedDateTime);

expect(component.selectedDateRangeOption).toBe(DateRangeOption.Custom);
expect(component.dateRange.start?.date()).toEqual(moment(updatedDateTime.value).date()); // Here's where it fails
expect(component.dateRange.end).toEqual(component.dateRange.end);
expect(component.dateRangeChange.emit).toHaveBeenCalledWith(component.dateRange);
expect(component.dateRangeChanged).toHaveBeenCalledTimes(1);
});
});

describe('endTimeChange', () => {
test('should emit updated input end date range with time', () => {
component.ngOnInit();
jest.spyOn(component, 'dateRangeChanged');

// any = MatDatepickerInputEvent<Date>
const updatedDateTime: any = {
value: new DateRange<moment.Moment>(component.dateRange.end, moment())
}

component.endTimeChange(updatedDateTime);

expect(component.selectedDateRangeOption).toBe(DateRangeOption.Custom);
expect(component.dateRange.start).toEqual(component.dateRange.start);
expect(component.dateRange.end?.date()).toEqual(moment(updatedDateTime.value).date()); // Here's where it fails
expect(component.dateRangeChange.emit).toHaveBeenCalledWith(component.dateRange);
expect(component.dateRangeChanged).toHaveBeenCalledTimes(1);
});
});

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