This is something that many admins and mods have been discussing for a while now, and I believe it would be an important feature for lemm.ee as well. Essentially, I would like to limit certain activities to users which meet specific requirements (maybe account age, amount of comments, etc). These activities might include things like image uploads, community creation, perhaps even private messages.

Sounds like the old karma requirements some reddit subs had. While I’m not against that, it would restrict locally registered users more so than others who are posting on lemm.ee communities when their host instance has no such system in place. I’m aware that if they post images those would be uploaded to their home instance and linked here with the patch you mentioned above, but the downside is that local users might feel inconvenienced more so than others. Not saying it’s a bad idea though, if we are thinking from a “protect lemm.ee” angle first and foremost.

Automated ML based NSFW scanning for all uploaded images

You might want to reach out to the dev of Sync for Lemmy, ljdawson on !syncforlemmy@lemmy.world, he just implemented an anti-NSFW upload feature in the app to do his part. Essentially, Sync users currently can’t post any kind of porn. While I don’t think that the CP spammers were using his particular app, or any app to begin with, I do think it’s a neat feature to have, but would make much more sense to run server-side.