Then instead of checking the IsOnGround bit, do a trace from the player to the ground. If the player stays on the same altitude/height for a second and according to the trace the player is not on the ground, the player is flying. Simple as that.
Of course hacked clients can work around this by moving the player up/down slightly and such things, but there are clients that do such thing
Of course hacked clients can work around this by moving the player up/down slightly and such things, but there are clients that do such thing