At this point on Win32 Qt might as well be the native UI. They did a better job of maintaining a coherent visual theme that says "Windows" and fits the design patterns than the actual owners of the platform.
I'd be more curious about that specific app. Niche bespoke commercial apps have this habit of being permanently stuck on old versions of Qt that don't handle these things as well as the newer versions. And until they are totally broken on Windows, the developers will never be motivated to lift a finger to fix this.
I have no idea if this is the case with P4V, but it absolutely is the case with a few other things I use.
Okay, too late to edit, but I decided to take a look.
The latest version of P4V actually is using Qt6, so I guess I have to stand somewhat corrected.
I'm just bitter about a couple of apps I use that are all permanently stuck on Qt4 where the vendor seems to have zero intention of caring to ever update them to a newer version of Qt. And ever since getting a HiDPI display, this has been continuously irritating me.
Personally I'd still advocate for Delphi / C++Builder there. The VCL (WinAPI wrapper plus very extensible for custom controls) behaves 'natively' because it is. And it's very nice to use.