Database
[{id:1,"email":"someemail@mail.com",unavailableDates:[ISODate("2022-09-08T18:30:00.000+00:00"),ISODate("2022-10-09T18:30:00.000+00:00"),ISODate("2021-12-31T18:30:00.000+00:00"),ISODate("2022-01-01T18:30:00.000+00:00")],sessionDate:ISODate("2021-12-31T18:30:00.000+00:00")}]
Query
db.collection.aggregate([{"$match":{"$expr":{"$in":["$sessionDate","$unavailableDates"]}}}])