In my experience, the main reason for the bans was an unsuccessful update, in particular, when trading a file with old product prices, it was most likely the reason for the crashes and then the ban. There may have been other reasons, but I definitely noticed this one a few times, including when chatting with other players.
There certainly is a problem with the update. I discovered an issue a few weeks ago during some tests.
If that is the only reason for the troubles on the server is currently unknown. Upcoming tests might be more conclusive but it is save to say that the launcher and anticheat used to be running perfectly fine years ago, but with all the updates done in the past years unexpected error sources were introduced (e.g. the difference between Singleplayer mode and Multiplayer has increased and switching between the modes back then did not have any noticable conflict while today it is a different story).
On top of that is that we actually do not really know the code of the anticheat (it never was published for security reasons), therefore it's a fair amount of guesswork and testing.
