Playing 1.07.25. Sometimes one of my cities will temporarily have the name, color, and stats of a neighboring empire instead of mine. This only affects the little bar that floats above the city. The info on the toolbar at the bottom of the screen, and the info on the floating window are correct. Which city of mine that is affected can change, and the name of the other faction's city can change as well.
I am playing as Altar, and other kingdom involved is Capitar.