My phone says it’s face-ID don’t work no more after putting it in water

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

To prevent liquid damage, avoid these:

• Swimming or bathing with your iPhone
• Exposing your iPhone to pressurized water or high velocity water, such as when showering, water skiing, wake boarding, surfing, jet skiing, and so on
• Using your iPhone in a sauna or steam room
• Intentionally submerging your iPhone in water
• Operating your iPhone outside the suggested temperature ranges or in extremely humid conditions
• Dropping your iPhone or subjecting it to other impacts
• Disassembling your iPhone, including removing screws

Because you put it in water? The iPhone is not waterproof, and while Apple markets it as “water resistant” they provide no coverage for water damaged devices.