Yea I remember when this a happened too .. I would download and run the latest XFree86 binaries instead of using the ones from Slackware. There was a whole kerfuffle about attribution. Xorg stayed GPL.

GPL/AGPL are for people who don't want their software to ever become part of an AWS/Azure offering or packaged commercially without code changes being released. But if you're writing a library in GPL (and it's not LGPL) don't expect anyone to use it. My current company has strict license checks as part of VC funding and we've removed and replaced parts of the code if it's discovered a dependent license is GPL (there's a CI check to prevent this now).