… In addition to the aforementioned new UI features, the Steam quick access menu now also houses Steam chat, making in-game socials easier, and there is now a new quick chat feature in Steam Deck and Big Picture mode. …
… Last, but not least, SteamOS will also yet again allow Bluetooth Wake for the Steam Deck LCD, and it enables wake from sleep for connected Steam Controllers. Source: Steam
… It also features various bug fixes, one of which is a fixed reticule at lower resolutions—no doubt a fix sorely wanted by Steam Deck gamers and others playing on handheld devices. Source: Steam Store