Mac OS has has this nailed down basically perfectly for over 10 years now, even windows has been great in the last 5+ years. Not having scaling done right in the age of 4k displays being cheap is a sin.
Fractional scaling in Windows is still eh, largely because they can't do a whole lot about icons not designed for that scale. For example in Rhino a bunch of the icons get weird pixel doubling when running 150% because they were designed for 100% and use a lot of 1 pixel wide elements.
It's honestly the main reason I keep hanging on to my now 10 and 15 year old displays. I'm hoping for a 6k 32" display so I can run true 200%. Dell makes one but they put a stupid webcam forehead on it.
I see scaling problems on Windows 11 (work PC) almost everywhere, in new dialogs and the older stuff. My own Linux box with Gnome has no issues; only webkit-gtk produces blurry fonts on some pages when my minimal font size conflicts with font-size of the page. This is a problem of the specific web page, I guess.
No HiDPI display here, btw. My old monitor is still good enough and fonts look awesome.
Disclaimer: I wear glasses and cannot see pixels where others might notice them. I increase font sizes everywhere, so font hinting has more to work with and everything looks sharp to me.
Legacy apps have problems in windows also, I guess in MacOS now basically you are not able to run them, but 3 years ago I remember same issues with old apps, blurry or pixelated...
The main issue is gnome not letting apps to scale themselves, whereas kde has just a toggle for that. So in gnome you have consistent size across monitors (cool) but blurry apps when running in xwayland (horrible)