When Mayfly is true for player, the player takes fall damage and seems to be jumping

When doing the /ability mayfly true command and you start flying, things seem normal to you. But you'll start taking fall damage the higher you go. And from other people's perspectives, you look like you are jumping up and down in the air, not flying. This also causes other issues such as getting caught on fire when flying over lava and so forth. This has been an issue for quite some time.