Delaying fall damage because of flying bug

NOTE: This is a duplicate of MC-267635. After I have been accused of using a non-standard client/server, this is the bug on a vanilla singleplayer minecraft world with a different video.

The bug
Disable fullscreen mode first. Jump from elevated terrain on a multiplayer server, press ESCAPE and right-click the window bar of windows. You are now flying in survival, adventure or creative mode. By joining on the server with another account, you can see that the player is flying too. When going back to the game, you will see that your damage gets delayed. This only works on Windows.

Video link: https://clipchamp.com/watch/1hr4P5WR6EP