I've used both the Apple MDP->Dual Link DVI adapter and a third party one. They both worked perfectly on my 2014 Mac Mini, and I had full brightness controls. The problem was when I got my Mac Studio, the brightness controls disappeared. This third party app fixed the problem.
What third party adapter are you using with you Mac Studio. And can you wake from sleep without issues?
I'm still using my third party MDP->dual link DVI adapter, and then I have an MDP->USB-C adapter on my Mac Studio, and the picture quality is as good as the 30" can look. The USB-C->dual link DVI adapter that I had caused little green sparkling lines to appear, so I think the setup is sound, at least for the moment.
I don't have any lines, or sparkling with the ASL adapter I'm using. The only issue is waking from sleep