When I start Firefox on Ubuntu under Wayland, Firefox behaves as if both shift keys just stopped working. In any text field pressing either Shift and any character inputs nothing, e.g. Shift+A inputs nothing instead of "A". This only happens in Firefox, not in any other app that I checked (terminal, Chrome). It also doesn't happen if I start Firefox in a Xorg session. Pasting such characters *does* work, e.g. I can paste "about:support" in the URL bar but not type it (":" requires shift). This also happens when I start Firefox in troubleshooting mode. What are the next steps in troubleshooting this?