[wasmperson]

I indeed did not know about this. There seem to be some caveats:

https://anubis.techaro.lol/docs/admin/configuration/challeng...

I guess for the meta refresh challenge it's less "proof of work" and more "proof of patience".

[xena]

The meta refresh challenge actually uses time as the proof! It makes sure you wait for at least 75% of the time the administrator configured and adds client side smear to ensure that browser temporal randomization doesn't trigger a false failure.