Do you notice blurriness on MacOS when the Settings app (name?) has been used to change the scaling factor to a fractional value?

Sorry, but I haven't ever used a Mac, so I unfortunately can't answer that. I've used Windows with fractional scaling, and most programs aren't blurry there, but the few that don't support fractional scaling are really blurry.

That's an accurate summary of my experience with Windows, too.