I advise to check the entity connects to the:
Microflows or Nanoflows: Review your microflows or nanoflows to ensure that there are no unintentional actions or updates that might be modifying the "ChangeDate" field.
Before/After Commit Events: In Mendix, you can define "Before Commit" and "After Commit" events that execute certain actions before or after an object is committed to the database. Check if you have any such events that might be inadvertently updating the "ChangeDate" field.
I hope this will help you.
Did you check the usages of the entity?
If you do this, do you see any result?