The problem of scraping content for models should be solved on a legal level. Trying to do it on a technical level is mostly futile, and wrong, because it actively makes legitimate uses worse.

If you really really really want a technical mitigation in addition to a legal one, then paywalls are vastly better than incredibly messy and problematic heuristic bot-detection. There's a huge payment problem for content anyway, so paywalls would mitigate or solve many other problems in addition to the AI-training-data one.