After monitoring the social channels over the past 12 hours or so, it appears the ban hammer has dropped on what could be thousands of accounts.
Posts starting popping up on Reddit and the official forums from players complaining about being banned. It’s hard to ascertain the reasons for bans from most posts but it seems that some may be a consequence of the Season to Eternal realm exploit that was doing the rounds before it was patched.
Most are likely to have come from using third-party apps but having looked at a lot of these, I think there have been a few that may have been incorrectly banned based on the post content. it’s hard to tell but you can usually get an idea from the writing in the post itself. In one post on Blizzard’s forums, there was Chia running in the background of a few people concerned their accounts had been banned (to do with crypto mining). There are always going to be some cases where there’s no wrongdoing but the majority will be for something dodgy.
Again, if you are caught up in the ban wave and don’t think you should be, contact Blizzard support. For anyone else who was banned using something against the rules, well, adios. You have been warned time and time again against using third-party apps.