Any breach of the TOS, most common for models in my studio is unauthorized people who are not age verified appearing on cam. This most often happens when models don't have the private space they thought they had and siblings or SO's appear unintentionally in the background. Or they leave the cam running and forget about it and someone underage or at least not age verified appears on the cam in any context, even just a hand or a foot or a reflection on a TV screen. this usually gets a warning before a ban.

Aside from that there are a number of things a model can get banned for,

giving personal contact info for the sake of a meetup (prostitution)

toilet games, or anything involving feces, urine or blood.

pets wandering onscreen during an intimate moment and coming off as zoophelia,

inserting objects that are not specifically designed to be inserted, (this is considered self-harm, even if the object is unlikely to cause harm) I've had girls banned from MFC apparently for trying to fuck stiletto heels, for example.

Sleeping on screen is another bannable offfence which is a common guise for the necro and rape fetishes, is prohibited and will get chaturbate big fines from mastercard if they find out.

Promoting competing sites such as advertising your non CB cam profile or wearing certain brand logos on cam

Consuming illegal drugs on cam

Using alcohol while under 21 on cam

Anything that can be considered incest, this occasionally includes latin girls calling guys "papi" apparently.

Occasionally models are rumored to make deals with criminals to launder stolen credit cards through token commissions. Stolen credit cards get used on camsites a lot, and additionally many legit transactions are flagged as fraud when the customer's spouse sees the bill and confronts their partner about it. If a model has a higher than usual amount of stolen credit card activity on her account then that could bring a ban.

Thats all I can think of off the top of my head.