My 2012 MacBook Pro has exactly the opposite behaviour on a clean install across multiple distros. The brightness keys do nothing until after a suspend, then work fine until the next reboot. Never found a fix.

Contrary to most advice, if you find something that’s compatible with a Wayland session (basically Gnome or Plasma) you might be pleasantly surprised.

I found that to be by far the closest I got to a macOS-like experience with Linux on a retina Mac, in terms of fluidity, trackpad scrolling and responsiveness.

If the Mac has a Retina display then I actually found XFCE runs worst of the various DEs at native resolution. Not in terms of resources but very choppy scrolling, video playback etc. Gnome and KDE Plasma actually ran better than XFCE for me on my 15” 2012 retina.

Presume it’s some kind of graphics acceleration thing, not 100% sure.