Perhaps it's a dead key in tour keyboard layout. If you press "e" after, do you get "é"?

You can choose a No Dead Keys layout, but then need to use a compose key to write accented characters.

I've never had this issue (running Nobara 39). I have no idea why that'd happen, but you could try the Flatpak version of Godot to see if it's more stable for you.

Here is the key I am referring to (Yes I have a qwertz keyboard, guten Tag)

Open a terminal and run xev. Then figure out what that key really is. Then open a bug report on godot github.

It's a meta key on Windows and Linux. Has nothing to do with godot. Press it again, or press escape.