This Fiddler Everywhere is trying to be more like Postman and less like original Fiddler Windows. It is also trying to turn Fiddler into a salable product with less functionality than the original Fiddler. I have mixed thoughts about this.
The glaring problem I have with this new app is that it lacks a "dark mode." I use the high-contrast color scheme on Windows forms as I do not want to exacerbate vision problems. Classic Fiddler has no problem with this. Fiddler Everywhere looks like a browser app which would need styling to make it high-contrast. I'll stick with Classic Fiddler for now.