The residential property where I live now rents out the basement below the high-rise building as a bathing center. Does this violate the relevant regulations of the state?

Absolutely illegal! ! ! Secondly, the condominium ownership belongs to the real right.

The condominium ownership of buildings includes the exclusive right of the exclusive part, the right of some parts (such as roof, garden and basement) and the right of membership. As far as the basement you mentioned is concerned, it belongs to all the owners of the community, and the community property has no ownership, so its behavior of renting the basement as a bathroom constitutes no right to dispose of it. The individual owners of the community can be independent or in the same direction.