This is becoming an issue at any CI provider that offers a free trial/tier as they try and stop third parties from using resources for crypto mining tasks. It may be that CircleCI automated validation tools need additional work to reduce the number of false positive results.
I’d gladly pay if I knew it’d resolve the issue, but it’s not obvious it would. Thanks for the link to support. They make it hard to find on purpose, of course.
If the system has blocked you it may be best not to try to make another account, even if you select a paid account until you have spoken to support. I do not know what they used to track blocked accounts, but if they use your IP address you could end up with the new account blocked as well.
The support link is not hard to find once you know the site as it is under main page / support / contact support within the page’s header. The problem is the different areas of the site do not display the same header details, It is a bit strange for it not to be included in the email message