I just tried this on a fully up to date install of Kubuntu focal 20.04, using the exact example link give in comment 3 and same firefox build.
Firefox successfully copied the repo clone link to the clipboard under KDE. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1866900 Title: Javascript clipboard does not work To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1866900/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs