YouTube ads just started appearing again, but as someone already suggested, uninstalling and reinstalling the plugin seems to resolve the issue (so far).
Fork Google.

This addon literally saved my life. Now that it's stopped working (on youtube), I'm instantly spiraling into uncontrollable depression after just 2 hours of exposure to ads. Patiently waiting for devs to send help.

This is amazing. If you are experiencing slip through ads especially on youtube, UNINSTALL AND REINSTALL the add on! <3 Thank you

9/10 this worked great and is a must use for the longest time but for some reason recently ads have been slipping through on youtube and some other unscrupulous websites

Absolutely necessary to use the modern web. Does a solid job of immediately blocking companies from stealing your private information, and makes that information largely useless. Also renders many pages actually usable.

If you're worried about content creators losing out on ad revenue, don't be. They're paid terribly across the board, ad revenue is barely anything.