A new Steam Deck client beta update was just pushed out. This one features a nice fix for Night mode automatically turning on and adding an Achievements page to the overlay when you press the "Steam" button while in game:

• Added Sucheng (Quick) keyboard for Traditional Chinese (requires Preview channel)
• Added Achievements page to overlay (while in-game press Steam button)
• Fixed notification for claiming digital rewards firing endlessly for some customers
• Fixed Night Mode automatically kicking in, even if the toggle is set to OFF
• Fixed desktop mode keyboard sometimes failing to show or dismiss

While the night mode is a nice fix, kept getting very confused when night mode would just turn on, the achievements page overlay is a super nice addition that will make achievement hunters very very happy!