You’re allowed to upload the same .mp4 file to multiple websites. There’s absolutely no reason why a creator that isn’t getting YouTube ad money couldn’t upload to YouTube and PeerTube at the same time. Presumably if they’re getting YouTube monetization, they have some kind of exclusivity agreement.
Seems unlikely that a creator would jump ship from a platform that pays them to a platform that doesn’t. That being said, lots of creators also constantly complain about demonetization, so maybe they’ll start to get fed up and move to purely in-video sponsorship things. Seems most likely from a creator that’s already on a platform like nebula
if it’s not free what’s the benefit of using PeerTube? You’re basically describing nebula