I'm not exactly sure where to post this, either the "Graphics" sub-forum or here. Since it seems to be only AMD related, I'm going to post it here under Drivers.
But yeah, there is some artifacting in this game that only occurs on certain AMD cards. I, myself, use a Radeon R7 260X and I experience some artifacting on the orbs that Zenyatta uses and some of the mobile carts you need to push in objective game modes.
Again: I'm only posting this here because it was already brought up on Blizzard's forums and it seems to be an AMD related issue, so I'm trying to bring it to their attention. Much love all.~