I would like to add that MP3tag not only removes V1 & V2 tags from flac files and writes only vorbis comments as tags, it also has an improved function to show flac files with ID3 tags
[2021-08-24] NEW: added reporting of existing ID3v1 tags in %_tag% for FLAC files. (#13156)
i would like to add that even though
MP3tag considers such constructions to be invalid and removes them, when instructed to do so.