Id like to make suggestion regarding the Tag Panel:
to highlight/colorize the border of its tag fields that have changed values. It would make them better stand out and visually distinguish them easier.
What I have in mind is the approach of Bulk Rename Utility which changes both the option's group border color (to red) and the group title (it gets a red background).
BRU screen capture (click to expand):
PS. Using Mp3Tag 3.20 x64 on win11.