Steam OS Build 20260824.1001 regressed Mesa to 26.1.2 before I was on mesa 26.1.8

Your system information

• Steam client version: Stable
• SteamOS version: Build: 20260824.1001 Version 3.10 Main
• Opted into Steam client beta?: [Yes/No] No
• Opted into SteamOS beta?: [Yes/No] Yes
• Have you checked for updates in Settings > System?: [Yes/No] Yes, Multiple times

Please describe your issue in as much detail as possible:

I was getting performance boost pre build 20260824.1001 version 3.10 as intel-vaapi-driver and mesa 26.1.8 mesa. Mesa extra version was a modified version 26.1.2 were rolled out in desktop mode. Now I am stuck on Mesa 26.1.2 with no updates when I switch to desktop mode

Steps for reproducing this issue:

1. Apply latest Build and Intel ANV Driver becomes 26.1.2 before update I was on 26.1.8 this applies to Mesa
2. Downgraded to beta and Stable drivers did not get updated

My Hardware:

CPU: Ryzen 5600x
GPU: Intel Arc B580 12GB Limited Edition
RAM 32 GB 3200mhz

According to the Steam OS Subreddit Mesa is now 26.1.99

Is there a way of forcing driver and Mesa updates ?

Start by comparing SteamOS build 20260824.1001 with the earlier build, focusing on the Mesa, Intel ANV, and intel-vaapi-driver versions reported in the issue. Check the SteamOS update path in desktop mode and whether switching between beta and stable changes the installed versions. Done means identifying why the update is missing or confirming the supported way to restore the expected driver versions.