Do they just ban you from playing BJ or do you get totally barred from the casino? Do they cap your betting and still let you play BJ?

What generally happens?

Why are you asking?

It varies widely and can change. Don't want to give you an irresponsible answer. If you're asking because you clean up at poker at a joint and want to take an amateur shot at counting a good 21 game they spread there are stories of lifetime property bans for simply appearing to count so why you want to know is often more important than the odds on favorite resolution in a garden variety case at a random location.

I've seen all of the actions you describe. Each casino is different and it often depends on the shift. One this is sure, if you decide to count cards and are playing a +ev game, you'll eventually get barred.

I think there are people who can play +ev at certain spots basically indefinitely. Could be an interesting prop bet.

I think that too.
Key word being "at certain spots", of course.

I lived in Vegas during 2015 through part of 2016, and it took me about 6 months to get banned from playing blackjack at nearly every property in Vegas, including downtown and all the locals casinos. Usually I would get "the tap," where a shift manager (or whoever) would appear and tell me I'm not allowed to play BJ, only the other table games. Sometimes I'd get approached as I cashed out at the cage. It got to the point where I'd go to some casino I had never even been to before, and they'd back me off immediately, right as I started to play. Obviously I was in some database and they had facial recognition.

Only one property, the SLS, banned me from the premises for life. It's probably because I played again after previously getting backed-off twice.

Most of the time the manager was nice, but occasionally they'd send some gruff security guard to watch me cash out.

The only casino that didn't seem to mind was the Venetian, and I'm not sure why. The only counter-measure they ever employed was to send the pit boss over, who would try to distract me by talking to me and asking a bunch of questions.

If you want to PM the casino I may be able to help. Some table games shifts enjoy threatening you with lifetime property wide bans mostly to scare you. These are things that can be appealed if you are able to get in touch with someone who's really in charge. If it's a tiny property, especially tribal where everyone personally knows each other, it becomes more difficult to get someone's ear. Employees won't want to step on each other's toes.

Had an incident where I wasn't even playing but hanging out with some girls (standing behind them) who were playing some min stakes carnival game. Pit supervisor (probably not even the shift boss but idk) comes up with security to kick me out and tell me I'm banned from this property (North America's most profitable casino) and all of it's sister tribal properties. At the red and green chip level, I'm definitely small potatoes here.

I eventually was able to get someone on the phone who told me my status on property is fine. The pit boss who found me to threaten / intimidate me told me I was banned for life (I was never asked to sign anything btw just to walk out) was just pulling $#*% out of his @ss and probably had no authority to make that claim. He did however get to high five his colleagues and say he kicked out probably the least intimidating AP in the joint.

AP backoff experiences are different depending on the employee(s) on duty. Most of my backoffs have been just that. Sometimes they're flat bets. In one place where I came back too soon, I was restricted at all table games including baccarat, which really shocked me... like I was some edge sorting mastermind (this was also pre-Ivey).

I ultimately feel that if your concern is to continue to go back to a property for other games, amenities, and/or dining, you'll be fine. If for some reason you're being asked to leave and never come back: 1) Don't sign anything. Try and be polite, calm, and leave peacefully. 2) Contact the casino later. In perhaps what one might describe as a remorseful manner (even though you didn't do anything wrong) explain that you understand you're not allowed to play blackjack but would like to continue to take advantage of XYZ on property. "Are you the person in charge who can make that decision for me?"

Advantage gambling leads to unpleasantness in many ways; however if you follow the teachings of those who've come before us, you'll be fine. If you're not fine, you may have a healthy legal settlement lol. I recommend following Bob Nercessian, author and lawyer in NV for advice on how to handle uncomfortable casino encounters and what casino employees are and aren't allowed to do to you.