Game graphics stuttering during brightness change in XDR displays

Ah, I found that it's regardless of Auto Brightness. Even if I manually adjust brightness, it stutters for the same reason (while other factors degrades performance simultaneously such as brightness/volume UI overlay). I believe this is XDR issue (at least in my environment).

Each stuttering takes several seconds. (sorry I didn't describe it)

In practice, stuttering happens for every tiny brightness change, totally dozens of times during playing games from afternoon to evening. I prefer keeping Auto Brightness on for almost all cases. Turning it off temporally will make it less usable because it forgets my preferred brightness curve and takes time to learn again.

Updates, in my environment:

This still exists in macOS 15.6.

I also found a strange thing – If the machine booted just recently, VSync pictures tends to be direct-to-display, until a strange state change. After that, VSync pictures couldn't go direct-to-display any longer. (Reason: Display rejected.) This isn't directly related to my game experience but I suspect it's also due to XDR issue.

Still occurred in macOS 26.0.1 (25A362) here.