Steam's beta client just turned HDR off when you stream to an OLED Steam Deck
Valve's beta Steam client now switches HDR off when it streams a game to an OLED Steam Deck. The change is a single line in a client note Valve titles October 9th, published at 00:42:30 UTC on October 10: "Disabled HDR when streaming to the OLED Steam Deck."

Valve's own Steam Deck photography on the device's Steam page. Image: Valve
The title and the timestamp are a day apart and cover one build. Valve dates its client notes by its own Pacific clock, where 00:42 UTC on October 10 is 17:42 on October 9. The post carried no later edit when it was read at 21:44 UTC on October 10.
Remote Play, the feature that streams a game running on one of your own machines to another device signed into your account, takes five further changes in the same build. Valve lists eight changes in all, six of them on streaming.
A save conflict could stop a stream launching
"Fixed streaming launch failing if the host client had a cloud conflict," Valve writes. The fault sits with the host, the machine actually running the game, rather than the device in your hands, and a cloud conflict is the state Steam reports when a local save and the copy in Steam Cloud disagree.
The next one is quieter: "Fixed the network health dialog popping up at the beginning of the stream." That is the panel Steam raises about connection quality, and it was appearing in the opening moments of a session.
Low bitrate, and a fallback when HEVC is missing
"Fixed dropping to a very low bitrate when hardware decoding is disabled," Valve says, so a client with hardware decoding switched off was losing picture quality too. If you want a sense of what bitrate buys in Steam's streaming stack, its newer convars carry one engineer's own sweep from 125 to 300 Mbit/s.
Two codec lines sit with it. "Automatically fall back to H.264 if HEVC isn't available" has the client pick the older codec by itself instead of stalling on the newer one, and "Enable Vulkan video decoding when using the SteamRT3C Linux beta" turns on Vulkan decoding for that runtime. SteamRT3C is Valve's own shorthand, and the note leaves it at that.
Both codec lines hand a decision to the client rather than to the player: H.264 when HEVC is unavailable, Vulkan decoding on the one Linux runtime where it had not been switched on. Both sit in the client rather than in any individual game.
All of it is on the beta channel
Valve sets the scope in the opening line: "We have just shipped an updated Steam Client to the Preview/Beta channel." None of it is in the stable client, and the note gives no date for when any of it might be.
The same build also makes Steam Frame controllers default to gamepad input in VR games that ship no VR bindings, which Valve says needs the beta channel on both the headset and the PC. Outside streaming, one more change tidies the QAM Voice Chat tab, adds a mute toggle to the volume sliders, and fixes the link that opens the active chat so it lands on the text box.
The pace on this channel is quick. Seven client notes carry dates from September 25 to October 9, and the one before this named two separate causes of a blank controller configurator and fixed both.
The HDR line is the one an owner meets without going looking for it. Stream a game to an OLED Deck on this build, and HDR no longer follows it across.