> let webWorkerURL = `${options.basePrefix}/.within.website/x/cmd/anubis/static/js/worker/sha256-${workerMethod}.mjs?cacheBuster=${options.version}`;

It looks like it's computing sha256 hashes. Such an ASIC friendly PoW has the downside that someone with ASICs would be able to either overwhelm the site or drive up the difficulty so high that CPUs can never get through.