Removing fields without changing time stamp of unchanged files

[LyricsLover]

@ehrlacher

but those are so many (30+) it makes no sense (and I have to check every time if there are new fields I didn't see before).

In such a case I suggest to have a look at the action called
"Remove fields except"
There you can define which tags you want to keep (and therefore delete all other, however they are called).

Remove Fields Except – Mp3tag Documentation

If you want to keep your embedded cover art, don't forget to include PICTURE in your list of tags to keep.

Please test such a new action with some of your files to be absolutely sure that you keep ALL your tags wanted. A backup of your data is always recommended.