a lot of apps look non-native on os X, with apple starting the trend of ignoring their own HIGs about 5 years ago.
I don't really mind, since osx happens to be my daily driver since about a year, but whenever people claim that osx is visually coherent I can't shake the feeling they are stuck in 1998 and Mac os 8.
The problem is that Qt and other cross-platform frameworks tend to look glitchy, as in their differences are non-intentional and jarring.
They also tend to just look pretty old-fashioned, because these frameworks are pretty old now and the controls, layouts, and workflows they provide are a bit old-fashioned.
So the first impression you get for software using Qt is old and glitchy. Which isn't great.
What's wrong with something looking "old-fashioned"? That seems to be better from my point of view.
I just finally got switched to Windows 10 on my work computer. Every time I start up a simple calculator, it takes up most of the space on my gigantic 27" QHD screen! Do they think I'm blind or something? The old Windows 7 calculator looked just fine and was an appropriate size.
Hmm. When I look at the (as far as I know) native apps that I have running on my Mac at this moment -- Safari, Day One, Numbers, Soulver, Terminal, MailMate, BBEdit -- there's a pretty obvious shared visual language between them. They all look "native Mac" in a way that Slack, Visual Code, LibreOffice, and Calibre don't. (To be fair, Calibre's UX goes out of its way not to fit in with any desktop environment on this planet, so it's probably not a good benchmark.)
They're in the uncanny valley.