I have Solus installed on a 2010 MacBook Pro (7,1):
Graphics card is: NVIDIA GeForce 320M and I'm using the Nouveau drivers -- the proprietary Nvidia 340.xx drivers are not very friendly (not confined to Solus).
This is a clean installation.
On waking from suspend, the screen goes to full brightness. When I hit the up or down brightness control (F1, F2) the screen returns to the previous setting and is adjusted from there.
I had the same problem when running Ubuntu 17.10 (with Wayland) recently (previously installed on this machine).