Have to engage Dev options. Settings > About > tap the Firefox icon a few times.

Thanks! TIL

If you are not using Firefox+uBO you really should, though!

Firefox + uBO for life.

How do I install this on Firefox desktop and Firefox Android? I remember there was an extension for Firefox the last time I checked. Now I cannot find the extension on the Mozilla store.

Isn’t Firefox open source? So isn’t it possible that anyone could see the changes being made even in the nightly versions? I’m not a programmer so forgive my ignorance.