I don't know that it's wrong, but it would be helpful if the box was ticked as soon as you made a change rather than when navigating away. Just so you can be sure.
What is 'wrong' about it, is that the check boxes only appear when you have selected multiple files, what suggests it has something to do with applying edits to multiple files. (or not)
(that's also what you will find as an explanation when you do a forum search on the matter)
But it seems we have established now that it serves as an indicator that will indicate that you have selected multiple files, and in that case it also indicates when you have edited a field. (only after you have navigated to another field)
But the latter purpose is not available when you have selected a single track.
Also, if it's purpose is indeed an 'undo' function, (besides that it should then also be available when editing a single track) it would probably be better to have it revert to showing the original values again after you unchecked the box.
Cut to the chase:
It's current purpose/function is ambivalent and not intuitive.
Not-a-bug, but room for improvement for sure.