End portal blocks don't look at all like what they do in pocket edition and have this weird effect that makes the texture look the same no matter what angle it is viewed from (somehow it's connected to the camera and is this odd sprite-like image). It's really hard to describe but I'm pretty sure it's not supposed to behave the way it is. Also affects end gateway blocks. I'm not sure if it affects windows computers (I assume not because no one else seems to have my issue), but it sure affects all my macs regardless of macOS version or computing power and the issue does NOT occur in pocket edition. I am aware that the texture was changed during the development of 1.9, but it wasn't until recently that I realized it's not supposed to look the way it does.

To reproduce just look at an end portal/gateway on a mac using any Minecraft version since 1.9 and move the camera around while looking at the portal block. It looks pretty wonky.

Notice in the attached images that even though the screenshots are from different camera angles, the end portal image is exactly the same (look near the crosshair and compare the screenshots if you don't believe me).