Thanks for reporting this.
Could you please confirm which device you are using when this happens (Android, Windows, or another platform)?
Also, please share at least your Anytype app version, and if possible:
• OS version
• the exact steps you followed before the dates shifted
Regarding your question about the workaround: currently it is not possible to change the default time for date properties (for example from 00:00 to 12:00).