Anubis has config for that: https://anubis.techaro.lol/docs/admin/policies#request-weigh...

It's up to the site admin to configure it that way, but it's possible some IP ranges/user agents are more often used by bots and therefore have an increased weight.

For old browsers there's also an option to use meta refresh instead of JS (https://anubis.techaro.lol/docs/admin/configuration/challeng...) but that's quite a recent addition and not enabled by default.