Hello,
OS: Encountered this problem on both Archlinux and CachyOS running KDE Wayland
Issue: Copy from browser, discord, or anything external does not paste into game client - in my case running CachyOS proton version.
Cause: Something broken between wayland copy paste and proton, might not be present for all versions of proton. X11 likely has no problem but I didn’t test it myself.
Fix is to use xclip and sync with wayland clipboard. Commands are for arch based systems, just change them for your OS if needed(ie “sudo apt install” for debian based):
sudo pacman -S xclip
paru -Ss clipboard-sync
https://github.com/dnut/clipboard-sync for other distro without AUR
systemctl --user enable --now clipboard-sync
Hope this helps someone. Would love input on other solutions as well.
Another possible fix is to try other proton versions, or X11 rather than KDE.