I maybe mistakes about why, but the fact is that greatly modern interface of version 1.5 still uses the same old, crude, whitish GUI for the feature of choosing colors from a palette. I reckon this is because this part of Everything does not utilize all that good stuff that came along with the arrival of dark mode to Windows
As you can see, the newer version has more modern look and bigger scale / area of colors - and I wish such change would be implemented also in Everything