Often, maybe a dozen times yearly, I have dreams where I'm in a bathroom or a locker room or a hopper room. I round a corner or open a door and it turns out there's a huge area attached to this water-aligned room, one I never saw before (even if the dream was taking place in a familiar setting).
Sometimes it's finding out that a bathroom at work suddenly continues and leads into further cubicles but with showers and sprayer nozzles and metal bathtubs. Sometimes it's going into a school bathroom and turning a corner and it leading into an entire pool area, with the tiling from the bathroom continued but now it's this aesthetically-lit 1920s institutional swimming complex.
I ran across a YouTube video a while back where someone (I think online-famous, not one I follow) said he had dreams where he stepped into the infinite bathroom (not sure if that's the term he used). Lots of people in the comments shared similar experiences. So I'm not special, but it's neat that it's a common theme.
My liminal dream bathrooms always have something besides just toilets, usually showers, but other people just go into a world where toilets stretch out forever, like a copy+paste of the real world bathroom.