@sero_one
If the goal is to post it publicly but still protect against scrapers, then it might be worth looking for a service that protects against AI scrapers and hosting your art there, and then putting the link to the art in your mastodon post.

As for the service, you could put it behind a website you set up, that is protected by Anubis and/or other scrapper blockers. Though there may be platforms that already do this for you.

It won't be as direct as simply putting the art on mastodon, so its up to you if such a setup will be worth it.