When server-authoritative-movement is turned to true, it sometimmes does not pick up on all of the movement. This results in either big or small desincs with the server. This can result in tping all over the place (in case correct player movement is set to true) very so othen. and when the delay is bigger, it can result in fe. radomly being set a blaze because the server thinks you are in a pit of lava (also happens without correct movement being on) while in reality on the client climbing a staircase. Both of those cases resulted in death and both happened in the timespan of about half a day.