For any poor soul coming across this issue - and in need of keeping iPad Pro 10.5 support:
<Canvas gl={{ powerPreference: 'default', antialias: false }} />
React-three-fiber uses defaults that make it heavier on memory than vanilla three.js - hence three examples keep working while R3F crashes with context loss. For Apple devices R3F enables both high DPR and antialiasing - which overloads the memory while having 0 visual difference. You can safely disable antialiasing on Canvas element - that makes iPads work again with no memory issues.