I've been using MP3Tag for years now and this is the first time this happened. MP3Tag Corrupts my files after I edit tags and album covers. The files did work before the edit. This problem started right after I Updated to the latest version.
Are you getting the files via ytmp3.cc?
I use mp3juices.cc to download all my music
I've downloaded an example file where the source was listed as Youtube and the resulting file is not an MP3 — despite having the MP3 file extension. It's an MP4 dash file using AAC as audio codec.
The fact the site is providing them with an *.mp3 extension is a serious mistake on their part and results in people polluting their libraries with camouflaged files. For obvious reasons, it's impossible to contact them and point out the issue. I'm also assuming the interest is elsewhere, since most of those sites are full of ads and try to force random malware on the visitors.
Please note that Mp3tag doesn't corrupt your files, but simply applies an ID3v2 tag to them (which you can also remove again). And please check the files for errors before making any assumptions about Mp3tag.