In general, 01.03.0400 didn’t work well in general with the new DJI GO 4 App. Video was laggy. Some parts of the new app weren’t even compatible with this old firmware. .0400 was just too old.
I updated to .0900 (the last version that you can remove the altitude limit) and it was released long ago enough that DJI hadn’t started making the Mavic worse in order to drive more sales of their new drones.
Works fine with the app now. I can’t do a range test just yet because it’s raining and gonnna be raining non stop for another week. Vancouver, I love you.