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.
That issue of handling more mouse buttons is now fixed today via this commit to the SDL library. Valve developer Sam Lantinga added the support for extended buttons on Wayland to properly handle this functionality with different gaming mice on Linux.