Gotta say I never heard of "Lyrics3" tags until you showed those examples, had to Google it and it seems like they are a PITA to remove.
MP3TAG couldn't do anything with the RIFFs. When I opened them in Tag Inspector, MB threw an error saying all files need to be the same format. Which led me to file explorer where I saw that the two files in question were WAV. Had MB convert to MP3, retagged the two files, rescanned the album, and refreshed in MP3TAG and the RIFF is gone.
It looks like LYRICS3 is WinAmp's implementation of .LRC, stored within the MP3 file. I rid of a number of them with MB's Tag Inspector, but there may be more. MP3TAG is rescaning the entire library and then I'll know if there are any remnants. If not, I' m done. If there are some, it shouldn't take much to make them disappear.And they're all gone.
The only minor issue, and I do mean minor, is that I've got tracks like the one in red that are not like the other 36346. And despite what you see about ID3v1, there are -no- tags in that format according to the Tag Inspector.
And these were also easily removed with MP3TAB by just changing the the 'remove' option to ID3v1. And whoosh they're gone.