I host my own instance and use the Creative Commons Non-Commerical license on my content. The idea is that this makes federation with other non-commercial instances no problem, but as soon as an instance mixes in ads in the feed, they (technically) can’t show my posts alongside it.
I know Pixelfed has a license field for every post/picture so you get fine grained control, but I don’t believe this is the case for the Mastodon API yet, so I have added the license information in my bio. It would be nice to attach license information to individual posts, and to assign a default license.
My hope is that this will make it more difficult for Meta and the like to mix in ads with my content. Time will tell if it works 😆
This is what I have done. Pixelfed has the option to assign a license to individual post, so it should not be that hard to implement the same for the rest of the fediverse.
I mainly choose the noncommercial license to stop big actors like Meta from displaying my content alongside their ads. They probably will not respect it, but if this becomes the standard on the social web, we might have some collective leverage down the road, i.e. for a class action lawsuit.