The Simple DirectMedia Library that is widely-used by many cross-platform games and part of the Steam Runtime now has better support for handling more mouse button events under Wayland.
Last week was a bug report over supporting more mouse buttons than five. While some mice end up binding their extra mouse buttons to keyboard keys, some mice such as when configured via Libratbag+Piper can map them to higher key press input event codes. Theoretically, allowing up to 48 key press input events in total.
You probably haven’t been running your games under wayland, even if your desktop is.
Proton only recently got Wayland support, and still does not enable it by default, so games usually run in xwayland.
Are you using the additional buttons for actions on the desktop, and if you are, maybe you bound them to keyboard button actions?
Now that I think about it, I’m realising I didn’t set it up specifically after switching from windows. It just kept doing the same things I set up before. It does mostly imitate keyboard input though, except for the ones I set as mouse actions (rapid L/R clicks) which still does that. Maybe the designers actually gave it some memory of its own. And yeah, the extra button use has all been in gaming so the proton/xwayland thing would make sense.
Gaming peripherals usually have internal memory for settings, yeah.
When you edit what a button does, it actually changes the input sent by the device in the firmware, so your mouse is likely just pretending to be a keyboard for those keys, and just internally running macros for the autoclicks.
It’s why you can set things up, and then close the config software.