Did you ever find a way to resolve this? I don’t recognise any of the names for the addons shown, but the exact same warnings are showing up in my logs too.
For anyone that has this issue and stumbles on this thread; the problem was down to having the repo for BestLibre added to my install, I was using it for the SyncThing addon for a while. Removed that and errors be gone.
I foolishly added a LOT of repos, and can no longer remove them, clicking the little trash can icon simply responds “Not a valid add-on repository” in red.