yes, total earth water is being depleted constantly, the Earth will get old and die.
using Hydrogen for fuel will exponentially speed up the dying process by depleting the earths precious water resource, and producing hydrogen for fuel has no environmental or logical advantage, unlike using oil for fuel.
but you are the smartest wall in the garden and have the Google search bias consensus to back you up ! I am sure Google will confirm that you need a COVID booster shot also
Water converting into H2 and oxygen and burning back into water again does not deplete the water supply.
The problem is net drain in energy to do either conversion.
Sorry, fraidy-cat, compared to the natural and biology processes that produce and consume hydrogen humans splitting water into hydrogen fuel is extremely minuscule and will have zero impact on the amount of hydrogen or water on this planet.
Nuclear fusion however, if we ever mastered, will reduce the amount of heavy hydrogen (deuterium) and thus the amount of heavy water on this planet as it consumes deuterium to form helium.