There is a greasyfork.org site, where users publish their scripts. However, the install button is not supported from it. STEPS TO REPRODUCE 1. Open a script page, for example https://greasyfork.org/ru/scripts/404304-youtube-download-video 2. Click green button Install This Script OBSERVED RESULT The page opens showing raw script content. EXPECTED RESULT A gracemonkey window opens, asking you to confirm you want to install script. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.23.90 KDE Frameworks Version: 5.90.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION This works normally for the openuserjs.org. For example, go to https://openuserjs.org/scripts/xthexder/Wide_GitHub, press Install button. And you will see gracemonkey confirm installation window appeared. As a workaround, you can of course copy and paste the script manually in gracemonkey.
Fixed in 3.2.0