Note: This update is for the Steam Deck Beta and Preview channels, and includes new features that are still being tested. You can opt into this in Settings > System > System Update Channel. General Fixed an issue causing a "Update Error" message when attempting to interact with the update menu on the 'Preview' update channel. An upcoming Steam Client beta update will unstick users encountering this issue.
SteamDeck公式情報
SteamOS 3.6.8 Beta: Updates for your Updates