Sprite rendering problems only on iPad mini

So, my team and I are experiencing an interesting issue. We're developing an app for the iPad mini. When I build the app for an iPad 4 or 2, it looks like this:

This is the way it's supposed to look. However, when my client receives the build on testflight on his iPad mini 4 (or even when he builds it himself from xCode), he sees the pictures below, and the app is extremely laggy and broken. The AR Camera we're using (Vuforia is in the project, but these issues persist even when all AR stuff is disabled) won't work. It looks like it could be some kind of rendering problem, but why it would happen on his iPad, and not any of mine, completely mystifies me. Can anyone explain this?

The specs for my friend's iPad are as such (he lives thousands of miles away, and there's no chance I can inspect the iPad personally).