[fsuts]

Water resistant is a lower threshold than waterproof, the latter being harder.

Many phones are water resistant with manufacturers guidance as to time and depth of water it can survive, eg iPhones https://support.apple.com/en-us/108039

As far as I’m aware, after you go to Apple or Samsung for a official battery replacement, there is no advisory issued to say the repair affected the previous level of water resistance

[andor]

In practice, repairs affect the water resistance, and Apple Store employees will confirm that to you. They just don't want to say so in the product description as it would raise doubts.