Censorship is already unethical. One would have establish a need for censorship first. Can a book be written, that causes people to become a danger and thus needs to be forbidden? Is it even possible that a text on a computer screen can cause harm to someone?

I'm not aware of this and any argument for censorship is usually quite a long stretch of hypertheticals.

For violating TOS people should know what rule they have violated. For example doxing, spamming or just being insufferably rude. Punishment without explanation or reason is obviously unethical.

I think shadow banning people and then actively keeping them in loop can hardly argued to be ethical. Shadow banning itself is barely ethical.