RAW seems like a flying creature could choose to drop prone and not invoke Opportunity Attacks as it falls away from adjacent enemies because it isn’t moving away using action, reaction, movement. Or, is dropping prone not an option while flying? It can drop prone like any other creature, then it falls about 500 feet. Probably better just to risk the oppy in most cases.

— Dan Dillon 👥 (@Dan_Dillon_1) February 17, 2020

and even if with the erratas, falling causes damage whether you hit anything or not? You take damage when you hit the ground or comparable surface.

If you’re higher than 500 feet up, you can maybe fall then recover on your next turn, the specifics of what are up to the DM.

— Dan Dillon 👥 (@Dan_Dillon_1) February 17, 2020