Hi ohrenkino, I’ll try to explain a bit better.
I’ve just looked at the Mp3tag configuration on my old Windows laptop to compare with the now changed configuration on my iMac (both v2.91). The Windows layout of the main Mp3tag is what I had on my iMac - the tag panel with the boxes: Title, Artist, Album, Year, Track, Genre, Comment, Directory, Album Artist, Composer, Disc Number and a square box for the album art, is on the left and PART of the main window, not a separate floating panel. The ‘floating’ panel, which is all I can seem to open, has a bar to the right to bring up all the fields into view as they can’t all be seen at the same time which I find very annoying. The tag panel on my laptop (and the one I had on my Mac) does not seem to be able to be moved by the mouse.
Hope this helps