Crazy high RAM usage on IOS

Hi, I've build an app for both android and IOS, and android has been running perfectly fine for months now. But IOS devices crash on a ram overflow error (EXC_RESOURCE RESOURCE_TYPE_MEMORY (limit=1450 MB, unused=0x0) on Iphone 7).

I've since reduced all the texture sizes (some were like 8k so this was a significant reduction) and I also compressed all the audio files. This got it working locally, but I've been rejected from the app store for crashing their test device (an Ipad).

I've never had any issues with Android, even on older devices with the uncompressed textures and audio, so why do these issues occur on IOS devices with far less memory usage?