If you’re no longer doing business with them, why not be vocal about why? If there’s a legitimate reason, it tells other partners where your line is so they know whether you’re a good fit for them. Don’t bad mouth them, but explain the facts and encourage viewers and other YouTubers to avoid them for the stated reasons.

I honestly don’t see what’s wrong with that. Steve from GN has done much worse and still gets sponsors, so it really can’t be that.