I hope this loophole only applies for waterproof devices that keep their warranty if they have water damage. The current system for all(?) IP68 devices is that water damage can be detected with liquid damage indicators and is seen as an accident. Accidents aren't covered by warranty so waterproofness of a device means .. nothing. As a side note, a Pixel 7 pro isn't waterproof.

I'm not sure if English is your first language, but that's not the exact wording from the document.

Emphasis mine:

To ensure the safety of end-users, this Regulation should provide for a limited derogation for portable batteries from the removability and replaceability requirements set for portable batteries concerning appliances that incorporate portable batteries and that are specifically designed to be used, for the majority of the active service of the appliance, in an environment that is regularly subject to splashing water, water streams or water immersion and that are intended to be washable or rinseable.

To me this would be things meant to be used in and around water (underwater cameras, water sensors, etc.), not water-resistant devices like smartphones that aren't specifically designed to be used in that kind of environment.