Black vertical and horizontal bars in 16:10 content

[RawBOT]

Your system information

• Device: Steam Deck OLED 1TB (Original LE)
• Steam client version: 1773426488
• SteamOS version: 3.7.20
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

In a recent SteamOS update, some specific 16:10 content shows the content centered in the screen, surrounded by vertical and horizontal black bars on top/bottom, and left/right, when using Gaming Mode. The content appears shrunk, it is not cut off. Using Stretch doesn't properly fill the screen either (contents get cut off), so it isn't a good workaround.

I have factory reset my Deck, and I'm still experiencing the issue. This didn't happen before, i.e. 4 months ago.

I have confirmed two unrelated software that present the issue:

• Slay the Spire 2

• Moonlight streaming (configured for native 1280x800 streaming), only when rendering the actual stream (not in menus).

Neither software presents this issue when run in Desktop Mode, i.e. it fills the screen as intended.

Further testing with StS2 shows that this also happens with 4:3. I think this is a bug with Gamescope.

Steps for reproducing this issue:

1. Launch Slay the Spire 2.
2. Go to Settings.
3. Set aspect ratio to 16:10 or 4:3.
4. Software is now surrounded by vertical and horizontal bars (appears shrunk).

[RawBOT]

These screenshots were taking in Game Mode, using the built-in Steam's screenshot functionality when using the built-in screen with no other display connected.

[RawBOT]

I have confirmed it is a Gamescope issue. As I mentioned, this issue didn't appear on regular desktop usage. However, when mounting Gamescope as a launch argument, e.g. gamescope -- %command%, then the issue presents again.

In Desktop mode, without Gamescope (no launch command):

With gamescope attached, i.e. gamescope -- %command%:

[kisak-valve]

Closing in favor of ValveSoftware/gamescope#2129.

[RawBOT]

Fixed in SteamOS 3.7.21.