Steam's broken voice chat volume sliders are finally fixed after nearly two years
A Steam bug that broke the voice chat volume sliders in the Steam Deck's Quick Access menu has been fixed in the October 16 beta, almost two years after it was reported. The owner who filed the reports closed them on October 19.

From the official Steam store gallery for No Man's Sky. Image: Hello Games
The first problem was that the slider handle sat slightly out of line, so it jumped when selected. The owner could reproduce it every time on the Steam Deck LCD and OLED and on a desktop in Big Picture mode.
The second made unmuting awkward. After muting the microphone or voice chat, the Reset to Default button did nothing, so the only way to unmute was to nudge the slider and press X. Older Steam builds had offered a simple Unmute option.

The next shot along in the same official No Man's Sky store gallery. Image: Hello Games
What the fix changes
Valve's beta notes say the voice chat volume slider's layout has been fixed and that friends' volume settings now persist between Steam sessions. According to the reporter, the sliders no longer have a Reset to Default option at all, but they now respond correctly to the gamepad shortcuts for muting and unmuting.

From the official Steam store gallery for Diablo IV. Image: Blizzard Entertainment, Inc.
Neither report received a reply from Valve in the two years they were open. The same beta also fixed a freeze when alt-tabbing out of Vulkan games on Linux.