Go to gnome.org, scroll down to "Developer Platform" and look at the title bar of the screenshot there. If you see a clean interface, then no reason other people give you will help.
But, if you do see the arrows there and think - why are there so many arrows and dots? It looks like bad UX. They you can see the issues others are talking about.
So you have a problem with a particular GTK application? Wow.
How about actually talking about the topic at hand, which is the gnome shell and its UX?
what an amazing example. We have on one window title bar:
- a "+"
- a down-arrow which presumably opens some sort of menu
- a hamburger menu (why is this different to the down arrow?)
- a "..." menu (err, isn't this the same as the hamburger menu and/or the down arrow?)
- A "hammer" icon next to the word "fetching". Because... Hammer Time! Also, yeah we use a hammer to fetch things. I think that's something we can all get behind.
- another two down-arrows. One probably opens out options for the "hammer" bar. The other...?
- an up and down arrow. Maybe this actually changes the options for the "hammer/fetching" bar.
- A search magnifying glass (no search field curiously).
- A cross.