From Redditors at /r/ClaudeAI this seems to be a common bug. People have got accounts back upon contacting them and I saw one even without doing anything, after a while...
I very much miss an official comment on this though.
It's not exactly inspiring confidence to subscribe to a product you may randomly be locked out from, with no comment from the company behind it.
In lieu of an official comment: the fraud detection that we run on account signup was overly aggressive, especially in response to the massive attention we've seen/new shapes of attacks. We've tuned it down and unbanned a number of accounts. If you're still seeing issues with your account specifically let me know the account at bkrausz at anthropic.com and I'll dig into it.
I very much miss an official comment on this though.
It's not exactly inspiring confidence to subscribe to a product you may randomly be locked out from, with no comment from the company behind it.