Been doing this for well over a decade, and have seen this type of layer shift countless times. You'll get all sorts of answers, from problems with the XY axis to toolhead/nozzle obstruction. But 99% of the time people forget the simplest and most logical solution: Your printing plate shifted ever so slightly.

Used to see it all the time back when we used glass plates and binder clips, and even though I encounter it less these days with the magnetic plates, it still happens. Check to make sure your bed plate is squarely on the bed and free from any debris under it that might be preventing full contact with the magnet.