I just purchased an X-H2S, and took it into the backyard to try the bird detect focus. It actually captured a hummingbird that was moving around really fast. But when I opened the files in Lightroom, I was shocked at the amount of sensor dust that was visible against the sky. It was everywhere. I was thinking, "Hey Fuji, at least let me get my own sensor dirty."
It turned out to be gnats that were flying around my backyard. I took some more photos of the blank sky at another location at f/16 and could barely see one faint speck of dust.