screen brightness not working after upgrade to 22.1

Distribution

22.1

Package version

6.4.8

Graphics hardware in use

Intel Corporation UHD Graphics 620

Frequency

Always

Bug description

On my Thinkpad L480, brightness controls stopped working after upgrade from 22.0 to 22.1. The brightness controls will move the on-screen slider display one notch up and down, but do not change display brightness, and the slider seems to only move one notch.

sudo brightnessctl s 10% work fine and changes the brightness to any value and this is reflected in the on-screen slider.

Steps to reproduce

Upgrade to Thinkpad L480 to Linux Mint Cinnamon 22.1 from 22.0
Attempt to change brightness with laptop brightness controls.

Expected behavior

Display brightness changes.

Additional information

Seemed at first to be a permissions problem - the default user is not part of the video group.

However, even with the correct permissions, the brightness control does not work.

No source file, test, or entry point is identified in the report. Start by reproducing the issue on a ThinkPad L480 running Linux Mint Cinnamon 22.1 with Intel UHD Graphics 620, then trace the laptop brightness-control path; done means the hardware controls change brightness beyond one slider notch while retaining the working brightnessctl behavior.