its an agency + bot or just scheduled messages (OF may have a built in system). almost if not every single message/pic set you get is automated, and you only talk with a person when you send a message back. Its also why her messages you get out of the blue dissapear, because its scheduled to get deleted as well.
there are 3 or 4 other accounts that are run in 100% the same way that she advertises as "hey sub to my friend stellablackxo", with the same wording used in the mass locked messages they send. If i message i get a response within like 2 minutes, and ive never bought or spent a dime in like 8 months of being subbed but yet they 100% reply every time, so if it is the same people responding, they are likely employees directed to humor every encounter on the chance it turns into a sale.
and id also say if she starts doing nudes, you will know 10000% because #1 it will be 50000$, and #2 imo if she does do nudes, it won't be a secret or you have to spend a lot before you get a chance. If she sold them to a select few people, then if they did get leaked, she loses out on all the people who would have bought if they knew, but got it from other sources.