ddcci-driver-linux VS bluekvm

There is an out-of-tree kernel module that exposes the DDC-CI interface as a regular brightness control, so any laptop-oriented brightness control tool will work afterwards.

Those tools use the kernel backlight system, which doesn't support external monitors out of the box. It's the same with Xorg. You can get the ddcci-backlight driver: https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/

To add to this: if you install ddcci-driver-linux GNOME should be able to control your brightness again. This removes the need for any extensions, and it's what I've been using for my monitor for the last few years.

There is an out of tree kernel module doing just that (integrating ddc/ci, the control channel for external monitor*, with the backlight system). And someone is working on upstreaming it

This is kinda a self promotion but for the brightness issue https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux may fix it. Or https://gitlab.com/YusufKhanAbdulHalim/ddcci-driver-linux/-/tree/master may fix it(if the first one doesnt work use the second one).

There is an unofficial Linux kernel module that allows userspace control of brightness (in a similar way to how laptop brightness is controllable):

https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux

I wrote a little script to do this automatically when your bluetooth keyboard switches between computers. I just updated it to work with m1 Macs based on the recent work.

See https://github.com/mikecarlton/bluekvm