Master Data Services: Weird automatic Date conversion

After migrating to MDS2019 there is now an issue when adding members to our entities. We have a datetime column with an input mask dd/mm/yyyy, however when adding a member and filling in the date a weird automatic conversion happens. Everything works fine when filling in dates till the 28th of the month (e.g. 28/12/2020), however continuing these dates filling in 29/12/2020, 30/12/2020 and 31/12/2020 automatically changes to 01/12/2020, 02/12/2020 and 03/12/2020 respectively. This does not happen when filling in the date in American format (MM/dd/yyyy) altough the inputmask definitely is dd/mm/yyyy. Is there someone who knows how this occurs?

Best,
Erik Jan