I wash my iPhone like every month. As I do with all of my phones for the past decade. Zero issues. I had a problem only once a long time ago, when I was in water with one of my Sony, but they replaced it immediately. No issue with the replacement.

Yes, this happens to people all the time. The seals that keep water out degrade over time. New phones are generally ok, but heat, dirt, detergent/salt in water, etc. wear them down until they are not water resistant anymore.

This is also why almost none of the manufacturers will fix the device under warranty when there is water damage, despite the IP rating.

Even Apple themselvers recommend against submerging and iPhone in water:

To prevent liquid damage, avoid: [...] Intentionally submerging your iPhone in water

https://support.apple.com/en-us/108039

The water resistance in these phones exist so that the phone hopefully survives when they get wet accidentally (heavy rain, pool drop, etc.). Not to shower with the phone, cleaning it by putting it under the tap, or doing underwater photography. Usually, it survives, until the seals fail.

Most water rated devices will warn against wearing them in the shower/bath because surfactants (soaps) let water penetrate a lot easier.

I take photos underwater (<2m) with my iphones all the time, all the way back to the iphone 6, never had any issues.

My old iPhone 13 I used to take swimming daily in a salt pool, it was still running fine after 2 years of that, although the contacts in the lightning port did eventually corrode (now I can only charge it wirelessly)

I've used my iPhones for underwater photography with just a normal clearcase and never had any issues

I felt while running next to the sea and my iPhone bounced on the ground and ended up somewhere in a levee under water. We could call it until the battery ran out of power. So I guess it depends.

Dropped my iPhone in the toilet , never skipped a beat after that.

What? I have never had an issue with this with my iPhone.