Music in current form is a troublemaker, it's sufficient for small demo or prototype, but not advised way to play music in proper game.
Music subsystem doesn't cache files, so PlayMusic loads file each time, that will cause stutters - it will vary depending on computer, but it's never good thing. It should be reworked to allow similar usage as Sound subsystem - multiple music buffers/streams - but with proper music files, load all music in game loading stage, then just play selected stream. Special effects for music files like 3d or something aren't needed.
There is a simple workaround for this for example using SDL2, i posted an example somewhere on forum, so that should work on SteamDeck.
Reworking music subsystem to any other lib (bass, fmod, soloud etc) would be nice, breaking compatibility for older GLB versions may be issue for someone, but focusing on modern platforms, and proper functionality for games should be more important.
Changing all music to sound file types - *wav isn't best solution for all games, if you have more music tracks or they are longer the output on file size will be to high, not even that, loading time will be longer than it should be for such small game, for me it's mitigating sense of using optimized tool like GLB.
Greedy Mouse still loads fast, but does it have 1 music track or more?