​At an Airbnb, white multiple round dome flat topped things in ceilings, even as tall at 12 feet high

Hello! I’m staying at an Airbnb and I’m curious what these are? There are multiple scattered in every room even two like 4 feet apart from each other and very very high up on walls. Since they’re all high this is the best one I could get. Ignore the brown dots on this one as the other ones don’t have that (probably moisture or something).