Looking back through all my DNS query logs for 2026 my biggest dependency on github.io is a rule-set in uBlock.

       1358 ublockorigin.github.io
        446 curbengh.github.io
         24 loathingkernel.github.io
         22 ytdl-org.github.io
         16 moomoohk.github.io
          6 profanity-im.github.io
          5 gtfobins.github.io
          3 simonw.github.io

You think? I don't believe i have seen a single submission here using the github.io domain.

It's possible some submissions are hosted there on a user's domain and heavily themed, but i suspect it's just not a host for many submissions. I'm not verifying that; of course i may be wrong.