Relates to MC-194185.

If the player is the only entity within view (using F5 mode) and the player is picking up an item or experience orb at the same time, occasionally, the player's hitbox will shift for a few frames. This is unlike MC-194185, because in that bug, the hitboxes of entities shift upwards (not directly upwards; sometimes off to the side but always an increase of the Y coordinate). In this bug, the hitbox of the player can occasionally shift sideways (not vertically at all).

Having only one entity within view makes the results more consistent (if more than one entity is in view, then any one of the entities could have this effect, but it's usually only one entity per view that gets this effect).

I am attaching a recording of this as well so you can take a look at this yourself.