The dark theme was (still is) been progressivelly implemented along the versions.
The 2022 version was one of the firsts one, so some tools, windows etc, don't have the dark mode yet implemented.
The same for the tools... even in inventor 24, some tools have the new style, others are still in "work in progress".
It's more complicated then we think to create the tools windows... it takes some time.
As an example, fillet tool is already implemented as the new style, chamfer is still in implementation.
In each version, more and more tools and windows are implemented.

CCarreiras