When you are in a server, and you are riding a happy ghast, upon dismounting it while it is touching the ground, the server will kick you for flying.
When you are in a server, and you are riding a happy ghast, upon dismounting it while it is touching the ground, the server will kick you for flying.
I could not reproduce in 1.21.7 nor 1.21.8. Could you please provide a video of the issue happening with the F3 debug screen enabled?