My face id has broken beacuse It fell into water, but the iPhone is waterproof. How is that?

The iPhone is not waterproof. Some iPhones have a degree of water resistance under controlled test conditions, but that is not the same thing.

If you have broken your phone by immersing it in water, you’re not going to get repairs for free - let alone a free upgrade from a used iPhone 12 Pro (the phone listed in your tag line) to a new iPhone 15 Pro Max.

No iPhone is waterproof.

Nowhere does Apple ever state that they are.

Water damage is not covered by any warranty.

Mhd_keswani Said:

"My face id has broken beacuse It fell into water,[...]"

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Extracting the Water...

Take it to a Retailer:

The only inexpensive way I can think of(an it will cost money) is to take it to a retailer, seeing if they have a device that gets the water out of a phone. Retailers have these.

About splash, water, and dust resistance of iPhone 7 and later - Apple Support

These models have a rating of IP68 under IEC standard 60529 (maximum depth of 6 meters up to 30 minutes):

• iPhone 15
• iPhone 15 Plus
• iPhone 15 Pro
• iPhone 15 Pro Max
• iPhone 14
• iPhone 14 Plus
• iPhone 14 Pro 
• iPhone 14 Pro Max
• iPhone 13 
• iPhone 13 mini
• iPhone 13 Pro
• iPhone 13 Pro Max
• iPhone 12
• iPhone 12 mini
• iPhone 12 Pro
• iPhone 12 Pro Max