AFAIK unless something has changed, Discord will globally ban people if they are discovered to be using a non approved client. I have no idea how often this occurs. This came up because folks had created clients such as BetterDiscord that add features which Discord want to sell and add end-to-end encryption using OTR. Discord want to be able to log all messages and OTR breaks that functionality for the servers.
From a discord staff: "We currently don't intentionally block or disable third party clients or action the accounts of people who use them. We do monitor the traffic of spammers and we build heuristics around how to identify them -- and sometimes third party clients get caught up in that. [...] it's not us trying to block/come after well-behaved third party clients."
