This is pretty interesting: https://socialhub.activitypub.rocks/t/fep-5624-per-object-reply-control-policies/2666
Basically it's a proposed extension to #activityPub to indicate the original post is not expecting replies, which is very useful from a harassment and spam handling perspective.
Afaik, peertube already implements something like 'commentsEnabled', which does a similar thing.
(I'd boost @weex 's post for this, but it seems he forgot to post this particular proposal)