Reply from mesa3d project:
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Hello,
You can find the upcoming stable releases in the Mesa release calendar:
https://docs.mesa3d.org/release-calendar.html
Only the last two point releases receive stable updates.
Older versions are no longer supported and don't get new releases.
Please ask your distro maintainers to upgrade to a supported version.
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Any chance of debian 11 getting a newer version of mesa? Or else backport the fix? Thanks.