Any idea why DDC seems so flaky on Apple Silicon? Both Lunar and Dell's Display Manager crash, malfunction, or hang on a regular basis. It seems like the kind of thing that Apple would get right.

In my experience DDC was always flaky. I've started working with DDC a bit more than 5 years ago, but I've talked to people that did this both on Windows and Linux and they had the same experiences.

Most of the time it's not an OS problem, it's a combination of factors including the addition of Thunderbolt, using hubs/docks/adapters, monitors that have slow DDC response etc.

There has to be more to it than that. With my Dell monitor on M1 mini, Lunar can adjust the brightness before the first sleep, but after the first sleep and wake Lunar never works again until I reboot the machine. Something inside macOS gets stuck.

Of course, the OS is not without its problems. That could be related to a macOS bug where the I/O registry view of an app gets stuck, which appeared recently in Ventura and latest Monterey.

But that usually is fixed by restarting Lunar, can you try and see if this helps instead of having to restart the whole computer?