If you bind M3, M4 or M5 to an action (fire, melee, parry, ability) the action still happens even when in menus. I haven't been able to find any other keys that do this.
I discovered this bug while trying to troubleshoot a different bug of my melee keybind (bound to M4) getting stuck in a state of being constantly inputted even when I'm not pressing it. This bug leads to repeated heavy melees that I am unable to stop. Additionally, because of the UI feature that allows you to scroll menus by holding any mouse button and dragging, when I do run into the bug I am unable to rebind my melee key because the menu doesn't stop scrolling as I drag my mouse through the settings to fix the issue.
I discovered this bug while trying to troubleshoot a different bug of my melee keybind (bound to M4) getting stuck in a state of being constantly inputted even when I'm not pressing it. This bug leads to repeated heavy melees that I am unable to stop. Additionally, because of the UI feature that allows you to scroll menus by holding any mouse button and dragging, when I do run into the bug I am unable to rebind my melee key because the menu doesn't stop scrolling as I drag my mouse through the settings to fix the issue.