On an old MS Access 2016 app, I remember that the close button was on the right side of the form's title bar.
Form being maximized the close button was on the right side of the app:
Now I have noticed that my close button is imediately after the form's name, so way off the right side:
Is there a way to configure this title bar and close button position or is an update of Access that changed this behaviour?
No. This is a part of the design changes enforced in the latest update.
The reason is, that this design - where you also can reposition tabs - is more in line with what users see elsewhere.
You could, of course, add your own close button at the far right by setting its property Anchor to: Right.