Player can float in midair by opening chat or any GUI and right clicking game window

I've seen this bug where if a player falls from a high distance. An they hit "chat" keybind and right click outside games window they float.

 

I find that a problem with pvp. If someone falls in end for example and there paused like that and someone drops water they can just safely swim back up. I think it's a bug.

This also happens on our server and player been taking advantage of this bug.

Example, provided below from a youtube vid:

https://youtu.be/rGqnhr4nVug?t=268