Steam Deck OLED Frame Cap Broken Below 90 hz

[cameronbosch]

Describe the bug

When I set the frame cap in Gaming Mode to anything below 90 hz, the game seemed to be stuck at 40 - 45 hz no matter what I did (it did stay at 90 hz when I set the frame cap to 90 hz).

What did you expect to happen?

I expected the frame cap to apply appropriately (for example, setting it to 60 hz should cap the frame rate to 60 hz).

Output of rpm-ostree status

State: idle
Deployments:
  ostree-image-signed:docker://ghcr.io/ublue-os/bazzite-deck:stable
                   Digest: sha256:f9070c349af242e5d47ed9a7a21418c42694d71c5fa0e5567b3c92d5036d9ca2
                  Version: 40.20240728.0 (2024-07-28T16:39:55Z)
            SecAdvisories: 1 moderate
                     Diff: 247 upgraded, 1 downgraded, 23 removed, 23 added
          LayeredPackages: sunshine

● ostree-image-signed:docker://ghcr.io/ublue-os/bazzite-deck:stable
                   Digest: sha256:56e6286b623e843164af43e1bdc951bb365e8a9bb9c444e0f8130c346bef2f5e
                  Version: 40.20240722.0 (2024-07-22T14:32:51Z)
          LayeredPackages: sunshine

  ostree-image-signed:docker://ghcr.io/ublue-os/bazzite-deck:stable
                   Digest: sha256:82624ab8dc34f83515f74cdaa160683f342cc62b8dd2d485fa2d465385ec5fab
                  Version: 40.20240717.0 (2024-07-17T17:10:50Z)
          LayeredPackages: sunshine

Hardware

Steam Deck OLED

Extra information or context

Edit: After updating Bazzite earlier today (after posting this bug report), this seems to be occurring much less often, but it still seems to be happening occasionally.

Edit 2: It seems like this issue is very similar to mine, although this person has it happening with an ROG Ally X.