When loading chunks it is possible that changes made during or briefly before the load are not visible for some but are for others. An example: someone in my world had built something small and asked me to tp and come see it. I teleported to them and there was nothing there. They were standing on the build but to me it looked like they were standing on air. When I tried to stand on it, i simply fell through as if nothing were there, on his screen i was glitching up and down