So I start out with a 22mm diameter round part with a center hub. I add supports to the middle and now the part is 24mm, even though no supports are outside the 22mm perimeter.
Sure, I don't think it matters though as this isn't the only part i've seen it on. This is a 3mf, stl does it too. As soon as you add supports it goes from 22mm to 24mm. It doesn't print any different but sure is confusing when I made a 22mm part and it is showing as scaled.