too many fanfics have the guy be like "oh me and my wife are in an open relationship im totally allowed to have sex with other people." we need more fanfics with straight up infidelity ! adultery even !
They are already selling data to midjourney, and it's very likely your work is already being used to train their models because you have to OPT OUT of this, not opt in. Very scummy of them to roll this out unannounced.
since tumblr is going to start scraping blogs to train ai be sure to glaze and nightshade your art!! Not only will both of these programs protect your art from being copied but nightshade also poisons any ai that tries to steal it
here is some more info on these tools and where you can download them: