This is a client side mod, which disables flight for a configurable amount of time.
Simply install the mod, go to your configs, find the file called "flight_disabler_timer", and set it to the text in the file to the amount of time you want.
Now when you take damage, you will be unable to fly for an amount of seconds equal to the number you put in divided by 1000.
This is exclusively made for modpacks. I have literally no clue why you would want it otherwise.
