Zorin OS 15 has a some inconsistency in design

Hello
First of all I want to thank you guys for creating the most beautiful desktop operating system out there. What bothers me though is, that there is a bit of inconsistency in the design. There are basically three different kind of window designs:

1. The corners of system programs like nautilus, settings, calculator all have rounded corners both at the top and in the bottom, really well done.
2. The corners of right clicking on the desktop or on a folder are not round. The right click menu is just a square and it really does not match the design of the system programs. What makes it a bit worse is that if I right click an app on the panel, the right click menu actually has rounded corners.
3. The corners of third party programs, like firefox, calendar, GIMP and actually even the Terminal all have rounded corners at the top only, the are not rounded at the bottom.

This means that I can have three different kind of corners open at the same time, and it really looks ugly. This is the same inconsistency that Windows 10 suffers from, it feels like eacch program was designed by itself instead of having a theme that is the same everywhere. The colors are consistent though, the are the same everywhere.

Is there any reason for why you have done this? It's clear that you have been doing a lot of work, so this must have been seen during the design. On Ubuntu I "just" apply a theme with rounded corners and then everything is rounded. What is stopping you from doing this?

Thank you for your time.

I have noticed the same thing.
The effect is not as present in the XFCE version.
But the gnome shell and window management seem to be different groups. I ran into this when I first tried to apply a theme. The theme applied to some things, but not to others- some things use GTK2 and others use GTK3.
I was able to fix it by modifying (heavily) my GTK theme and ended up studying how to write .css and making my own where I could define all the parameters. It was a strictly amateur effort, but it did work. Initially I considered going all the way, getting good at it and writing themes for GTK3 since all the modern GTK themes are flat n pasty with vibrant rainbowy colors.
Three weeks in, I decided I prefer being a mechanic.