Hi Pauli,
Just started an upgrade to Canary on another laptop, before upgrading to 25314, W.U. downloaded this Graphics driver for the Intel Graphics 620 adapter, Version 30.0.100.9670 dated June/9/2021.
We'll see if it changes after the upgrade.
Could you please check which version you got on your Intel Graphics 630 that is failing the brightness adjustment?
Thanks.