PSA 10 is ‘virtually perfect’ and not necessarily Pristine/Black Label level of perfect. So there’s a bit of room for a tiny flaw, like slightly off-centered one direction or a tiny edge/corner chip or some minor surface flaw.
It’s almost impossible to have a completely perfect WOTC holo card due to the manufacturing defects they have. I have a couple PSA 10 WOTC holos with a similar chip on the bottom edge, but no other flaws.