Lol it's not hacking... All you do is jump and grab Blockland window and move it. It makes you lag but you stay in the air.
i believe the float hack is based around lag, where whenever the movement packets are not sent, it tricks the server into thinking that the player is not moving at all, giving it the properties of floating. i am probably wrong though
and moving a window like that causes the process to freeze, due to software limitations(?)