I'm assuming they haven't yet sent responses to the bots? Since AI is dumb, you can send errors that tell the bot to git clone rather than crawl. If it's vulnerable to prompt injection, it might listen and do the clone instead and stop trying to solve challenges.

Barring that, I think the solution is to charge money for access. Require users to sign up to render HTML, and provide a form of payment (any form you want). The cost is, say, $0.1 per GB. Rate limit all requests to reduce CPU. For the average user this will cost a few cents. For the bots you'll cover your costs and have a rate limiter to keep your system from being overwhelmed. Or they can git clone for free with no limit.