It’d be news to me, I’ve used the same userChrome.css and userContent.css for years now and I keep my Gentoo Linux desktop up to date with weekly updates, so the Firefox I’m using is confirmed to be the latest version.
Additionally, a quick search on ddg reveals no recent mentions nor plans for deprecation of the feature as far as I can tell.
It’d be news to me, I’ve used the same userChrome.css and userContent.css for years now and I keep my Gentoo Linux desktop up to date with weekly updates, so the Firefox I’m using is confirmed to be the latest version.
Additionally, a quick search on ddg reveals no recent mentions nor plans for deprecation of the feature as far as I can tell.
I found this Reddit discussion
The timeline fits (pre-covid), but I got the word wrong. I thought userchrome would’ve been killed of by now.