For those who don't want their art fed into Twitter's AI, you can opt out in the settings under "Privacy and Safety" >> "Grok"

I noticed after opting out on PC that I was still opted in on the android app, so Twitter users will probably have to opt out on each device individually

As a hobby artist, I don't mind letting my personal works be used to train AI, but I'm still going to opt out of data sharing on Twitter because I use my account to post art commissioned from other artists who did not give permission to have their art used to train AI