Gliching into blocks

Im not sure about the version but its at 18.12.2020 the newest version but i think its 1.16.201.

the but is when you stand on the floor you could glich into the blocks besite you.

it isnt always just sometimes but i dont know why.

maybe its because im standing on a chest.

after a bit it stops and minecraft is normal again, ill show you in a video.