The TLDW: on the Xiaomi 13 ultra the 75mm equivalent lens is actually a 60mm lens. It crops in at 75mm in auto mode but when using raw it just outputs the 60mm instead.
From the YT channel: How many dives / pressure cycles can a carbon fiber submarine / submersible / pressure vessel take? How fast does the material weaken by continuous trips to close to it’s crush depth / implosion pressure?