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.
These notes contain all changes since the current stable SteamOS 3.7 release, with the new changes since the previous 3.8.3 Beta noted below
New in 3.8.4
Fixed a regression causing certain VRR-capable TVs to fail to work via a connected dock
Fixed a rare bug where switching to desktop mode may hang indefinitely
Fixes for experimental nested desktop mode
Even more stability and security updates
Even more support for upcoming Steam Machine hardware
General
Fixed a case where WiFi performance could become degraded until the device was put to sleep or manually reconnected
Fixed excessive trackpad sensitivity on certain early Steam Deck LCD models
Initial support for upcoming Steam Machine hardware
Added support for waking from sleep via connected Steam Controller
Updated Arch system base
Updated graphics driver with performance and stability fixes
Fixed a case where per-app performance settings would intermittently fail to apply when launching a game
Substantially improved speed of future OS updates on high-speed connections
Improved support for the screencasts in Game Mode (e.g. OBS/Discord)
Fixed dropdown menus not appearing in some games
Improved VRR frame pacing
Fixed FSR badge remaining off in the performance overlay, even if it was actually active
Improved support for games that attempt to open PDF files in external viewers
Added missing graphics features needed for titles such as "Crimson Desert"
Fixed an issue affecting certain titles (such as "SpongeBob SquarePants: Titans of the Tide") where the game window could have an incorrect position
Fixed closing certain titles (such as "STAR WARS Jedi: Survivor™") and Starfield resulting in a session crash
Improved support for certain USB racing wheels and USB devices that boot in a non-standard mode
Steam Deck controller firmware updates now display update progress on the splash screen
Fixes issue on specific Steam Deck revisions where firmware updates could render the left controller inoperative for that session
Numerous stability and security updates
Bluetooth
Audio
Detect HDMI channel count and expose surround configuration if available
Add a setting to allow using Bluetooth headset mics (Bluetooth playback quality will be worse while capture is active)
Restore internal audio device on reboot if set to "Off" in desktop mode
Increase suspend timeout for HDMI devices so initial audio isn't cut off after a few seconds of inactivity
Fixed a bug with switching input devices when a wired headset is plugged in
Fixed an issue where audio underruns could be experienced after sleep/resume
Accessibility
Desktop Mode
KDE Plasma updated to version 6.4.3 from 6.2.5, and now uses wayland by default
Fixes several cases of reduced performance in Desktop Mode compared to Game Mode
Improved support for rotated displays
Better scale factor out of the box on TVs
Adds support for external HDR displays
Adds support for VRR displays
Adds support per-display scale factor
For more information, see Plasma release announcements
Keyboard layout and language are now obeying Game Mode settings
Improved windowing behavior for games running in Proton
System Firmware
Non-Deck
Improved compatibility with recent Intel and AMD platforms
Greatly improved video memory management with discrete GPU platforms
Fixed a compatibility issue with the SteamOS chainloader that could cause a boot failure on some desktop systems with recent UEFI firmware
Power button short and long presses now supported across a wide variety of devices
Improved controller support for OneXPlayer F1 series, GPD Win 5, GPD Win Mini, Anbernic Win600, OrangePi NEO, and Lenovo Legion Go
Added controller support for OneXPlayer X1 series and Lenovo Legion Go 2
Added system and controller firmware update support for the Lenovo Legion Go 2
Added preliminary charge limiting support for Legion Go, Legion Go S, and Legion Go 2 - currently only accessible in Desktop Mode
Added controller RGB LED color settings for the Lenovo Legion Go 2
Added controller, TDP control, and speaker audio support for the ASUS ROG Xbox Ally series
Reduced handheld controller input latency from 5-8ms to 100-500us
Night mode, color vibrance, and color temperature sliders in Steam now work on Z2E and later AMD APUs
Seamless boot fixes for Z2E and later AMD APUs
Automatically handle internally rotated display for some third-party handhelds
Improved motion control support for handhelds with BMI260 IMUs
SD card reliability improvements for some third-party handhelds, including ASUS ROG Xbox Ally, Legion Go 1, Legion Go S, Legion Go 2, and MSI Claw
Fixed washed out colors for Zotac and OneXPlayer handhelds with OLED
Fixed some GPU hangs on Phoenix APU devices (Tales of Arise, Octopath Traveler II)
Fixed ASUS ROG Ally power consumption from fingerprint reader while shut down
Fixed trackpad losing functionality after sleep/resume on the Legion Go
Fixed spurious wake-ups when using a Logitech Bolt receiver
Developer
Desktop Mode now uses Wayland by default
Updated Linux kernel to 6.16
Steam now uses steamos-manager to query available desktop sessions and trigger desktop session switching
Added support for setting the desktop password in developer settings
Initial support for running as a Virtual Machine guest (virtio guest drivers)
Added support for third-party devices to trigger the SteamOS boot menu via EFI variable
Added `custom-update` verb to `atomupd-manager` for easier testing of specific builds
System reports now include more audio debug information
Initial support for LAVD CPU scheduler via `steamosctl set-cpu-scheduler lavd`
