I use Manjaro with the GNOME desktop, and I’m on the testing branch. I’ve recently noticed (perhaps after the update to Gnome 40? I can’t tell for sure) that the compose key that I have set is disabled after every reboot. If I open gnome-tweaks and re-enable it, it remains active for the session, and that it’s disabled again at the next reboot.
P.S. Most likely unrelated: when gnome-tweaks is launched and closed, it will never launch again in that session. Trying to launch it in a terminal will result in a "Failed to register: Timeout was reached"
message.