seen it in alot of runs but why do they do that? then they teleport or something can someone explain

if you press f by mistake it opens

no profily that is dead wrong

when you press cancel on the purchase menu, the game will give you the ability to move during cutscenes, obtained with a groundpound or dive. this allows you to collect ice creams earlier, collect ice creams twice (sicwarp, the "teleport" you were describing i would assume), bypass the loss of control during door animations (another possible "teleport"), and just move during any part of the game where you're frozen still (EXCEPT WHEN YOU'RE IN WATER!!!).

oh well i do it by mistake when I press f so...

f is there on purpose

yes