There is not much you can actually do about that, even if blocking it on the device, you could just take out your phone and take a picture. Would be the same problem on OnlyFan or X. I guess you can could go for legal action if sharing protected content is a crime in your country, maybe at some point author / platform will need to create TOS, contract like to state that doing that is against the rule here but not much can be done technically as long as the data appear on a screen at least once. As Bradley suggested in another comment, you could downvote the person and expose him/her to the community.