Valve has recently shipped an update to the Steam Deck Client in the Preview/Beta channel. The updates are as follows:
General
Fixed a rare crash when hotplugging a mouse and keyboard
Improved caching of Soundtrack album covers in library
Steam Input
Added visualization of mode shifts to the Preview Layout page
Added the ability to have a mode shift without needing to have a mode already on a source
Fixed a case where mode shift bindings leftover from a bug in 2019 could activate a mode shift that was disabled in the UI
Fixed detecting thumbsticks that have been mapped to a D-pad in controller setup