nprofile1qy2hwumn8ghj7un9d3shjtnddaehgu3wwp6kyqpq7lgy0rj5a2nwpnyc4hup6ufpfz7wz6dzcgd3crm6fm2yd34dcz0qrh5lc3 (nprofile…5lc3) There’s a lot of good work being done here: https://github.com/ai-robots-txt/ai.robots.txt
This repo also has server configuration that will deny access to matching user agents (not just asking them nicely to go away via robots.txt). Of course it’s only as effective as honest crawlers that send a genuine UA string, but it’s a start.