Nginx reverse proxy gets blocked
Solution 1:
If the "cheap shared hosting" supports it, you could forward the original requester IP:proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
So hopefully your reverse proxy's IP wont gets blocked.
If you want to block a list of bots you can check this question/answer out:
https://stackoverflow.com/a/24820722/940009