If you look in the screenshot, you can see what I mean. These meshes have the same index count as they do vertex count according to Xcode, but in Unity, they have way less (about 1/6 as many) indices as they do triangles.
So it seems that either Xcode is reporting wrong, or Unity is not correctly creating these meshes on iOS
What Xcode reports is (if we take #69 as an example) “take index buffer with pointer 0x10c21ca00, interpret data as 16-bit unsigned integers, use 1536 indices starting from offset 0, render distinct triangles; render 30 instances”. This will end up rendering a mesh with 512 triangles 30 times.