There seems to be a new audio issue related to using the Steam Link's flatpak in the Steam Deck's game mode while connected to a TV with any dock.

Everything works fine until the Link's quick settings bar is opened (guide button held down), at which point the audio suddenly starts to have horrible distortion, echo, and drastically increased volume. The issue persists for any and all streamed audio until the streaming connection is disconnected - upon reconnection, it works fine until you interact with the Quick Settings again.

The issue has recently appeared, most likely due to the latest flatpak update (1.3.7). Tested various docks and stable/beta branches of both client and host Steam. The issue doesn't appear when using Steam Deck in handheld mode. I've also rolled back to the latest flatpak version on Flathub to test, but it refused to connect to the host (stuck on the connecting/loading screen).