hasSome() not working with Date object

This console.log might be misleading as it only logs at the second level, where the actual date value is in milliseconds.
If you want to be sure the value matches you should compare at the ms level.
Something like:

const hasSomeDate = new Date(2022,5,1,15,0);
console.log('Query value:',  hasSomeDate.getTime());
return query.find()
.then({items}) => {
const dateTimeSlots = items.map(e => e.dateTimeSlot.getTime());
console.log('dateTimeSlots: ', dateTimeSlots );
console.log('is included', dateTimeSlots.includes(hasSomeDate.getTime()); 
})