What happened to the iPhone 12 Pro Max?
The iPhone 12 Pro Max was never fixed before it went blank in shallow water, which means the water resistance adhesive was intact and the phone was supposed to resist water as the follow specification(from Apple website):
Rated IP68 (maximum depth of 6 metres up to 30 minutes) under IEC standard 60529
As to the water resistance above, you can use the phone under water less than 6 metres up to 30 minutes without the risk of damaging it.
How water damaged it is
Why isn't the phone water resistant as specification says?
The right way to understand iPhone water resistance specification.