I'm probably missing something but it seems like every app I use on iOS is basically an island. Even among Apple apps there seems to be different UX guidelines

I'm probably missing something but it seems like every app I use on iOS is basically an island. Even among Apple apps there seems to be different UX guidelines at play. To me iOS apps feel a lot like flash sites in the late 90s/early 00s in terms of the variety of interfaces. So it doesn't feel out of place to me. The only thing jarring for me is how bright red it is. Not a fan of that.