iphone 11 is not water resistant

It is not "waterproof". Apple says this about its resistance:

About splash, water, and dust resistance of iPhone 7 and later - https://support.apple.com/HT207043

and:

Liquid damage to iPhone or iPod isn't covered by warranty - http://support.apple.com/HT204104 - "iPhone and most iPod devices are equipped with Liquid Contact Indicators (LCIs) that you can see from the outside."

Take it to a Genius Bar for evaluation but be prepared to pay for out-of warranty repair (reduced cost it you have Applecare).

No, Appe never said anything about your phone surviving being submerged in water.

You misunderstood the testing method of water resistance with suggestion fir use.

Apple's official statement is never submerge your iPhone in liquid.

https://support.apple.com/en-us/HT207043

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

No phone is truly water-proof or water resistant. Also the Steam of the Hot Water of your shower isn't good for electronics. Do not get the device in touch with any liquid. Apple only gives you theoretical values.

Your phone is likely damaged now, take it into an Apple Store for service, a repair or replacement unit will cost you, it depends on your country. With AppleCare+ a replacement would be 99$, without it it's 399$, at least for the US.

See: iPhone service pricing – United States

https://support.apple.com/iphone/repair/service/pricing

You know, they make Bluetooth speakers specially for using in the shower.

Everything needs to be taken with a bit of skepticism. The sealing materials are not permanently water resistant. Even if they manage to keep out water/dust/etc. after one or multiple exposures, each exposure degrades the sealing materials. And if you look at the description, there's always a reference to one or more footnotes. I'm pretty sure this was the source for the photo you posted:

iPhone 11 - Apple

Water resistant to twice the depth.

iPhone 11 is water resistant up to 2 meters for up to 30 minutes — double the depth of iPhone XR.1

1. iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max are splash, water, and dust resistant and were tested under controlled laboratory conditions; iPhone 11 Pro and iPhone 11 Pro Max have a rating of IP68 under IEC standard 60529 (maximum depth of 4 meters up to 30 minutes) and iPhone 11 has a rating of IP68 under IEC standard 60529 (maximum depth of 2 meters up to 30 minutes). Splash, water, and dust resistance are not permanent conditions and resistance might decrease as a result of normal wear. Do not attempt to charge a wet iPhone; refer to the user guide for cleaning and drying instructions. Liquid damage not covered under warranty.

Realize those test conditions are exactly that. Very, very gently and slowly immersing a brand new iPhone in water under laboratory conditions. It's like a showroom car saying it get an estimated 35mpg fuel efficiency on the highway. Sure, it was testing an unladen car on a rolling track with no wind resistance and probably using pure gasoline and not a winter ethanol mix. You know that car's probably only going to get 30 mpg once you head off across hilly territory. You also know the pure white milk the TV commercials show you pouring over cornflakes is really diluted Elmer's Glue.

Apple tells you not to expose the phone to high pressure water from a shower, or water from a shower bouncing back off onto a phone. If the iPhone is in your pocket and a few drops of water accidentally get in they you stand a chance of getting away with it. It's not designed to stand up to you testing the device with any deliberate exposure to water.

Your iPhone has been destroyed by the water and it must be replaced.

Apple will not attempt any repair on a water damaged device.

Did you use only cold water during this five minute shower?

Make a Genius Bar appointment with Apple and see what they say about your situation.

Apple doesn't care how long you owned it or how many drops of water got on it.

Water damage is not covered by the standard warranty and the device can not be repaired.

Water resistance is never a guarantee that water intrusion and water damage cannot occur when the device is exposed to water. All "resistant" means is it is less likely to be damaged from any given water exposure than a non-resistant device would be.

As you know, the responses posted here do not come from Apple, just users like you. Even if we were to say, "Oh, it is terribly unfair, Apple should make you a full refund for your iPhone plus $1000 for emotional distress," it would make not one iota of difference. We just thought you would like to know in advance Apple's likely reaction when you take your device for repair and the reasoning for it. In fact what Apple has to say about this is what is in the links to the documents I posted in my first reply, such as not taking the phone into extremely humid conditions, and if something goes wrong in any connection with liquid damage it will not be covered by the warranty.