Why is the iPhone xs/xs max not covered under warranty for water damage?

It is stated multiple times that these phones are water proof and it is "Rated IP68 (maximum depth of 2 meters up to 30 minutes) under IEC standard 60529". This is not a true statement. I accidentally knocked mine into the sink, but I pulled it right back out and it does still turn on and off, but the volume and ringer buttons are glitching and it isn't letting me swipe and water somehow got behind my camera.