I reported the same problem earlier in this thread, but I don't see it as a defect, incompatibility, etc. To me it's clear that it's a thermal issue and the phone is working as designed, even if it's not great for this application. My iPhones have always dimmed the screen for thermal management reasons if they got very hot, for example when sitting in a hot car. It's happened to me once since getting the
Mavic Air 2, on a hot day standing in the sun. All my other flights have been fine. It's obviously going to vary a lot depending on circumstances.