I’m assuming you came to macOS from some years using Windows?
...but I was also exposed to 90's Macs somewhat. I remember that my switch from the Amiga UI to Windows was fairly smooth, but I never got quite used to the Mac UI (not that it matters all that much though because I mostly switched back to the command line anyway, that's the only way to keep sane when switching regularly between Mac, Windows and Linux).
Visual Studio on Windows does drive me crazy for exactly this reason, especially as each instance can only have one top-level document (solution) open at a time.
I think the app vs window centric model really comes down to user preference - I think I could get used to window again but I had Chrome, Audacity, and the windows explorer open last night with maybe five windows and was alt-tabbing to all the wrong places. My brain just makes sense of “get to application, then find the window” better than a list of windows I have to sift through across disparate apps.
I agree with the scroll bars and settings getting worse. Buttons are either way, but - like app vs window switching - could be remedied with a setting to change the behavior.
Alt-Tab (erm... Cmd-Tab) switching through applications instead of windows (and then having a separate hotkey to tab through windows, but only within one application), and that mess combined with the fact that there can be UI applications that just have a menu bar but no open windows is just incredibly bizarre (and even though I'm now a primary Mac user for more than a decade it still feels incredibly clunky - at least there's this gesture-controlled 'exploded-desktop-view' as a workaround).
...and when it comes to the new stuff:
- hiding the scroll bar, what a completely non-sensical decision from a UX point of view, I now need to wiggle the touchpad to see where I am in a document, and how much of the document I'm currently viewing (yes I know that this can be disabled, and that's the first thing I do on a new Mac, along with inverting the scrolling direction)
- arranging buttons vertically in popup dialogs on macOS devices with landscape display orientation (arguably it makes sense on an iPhone with portrait display orientation, but in either case the vertical arrangement makes it a lot more likely to accidentally hit the wrong button)
- the new settings panel is just a massive step back from the old one (which wasn't all that great either)
- don't even get me started on iOS, if you don't know the 'magic gestures' nothing makes sense (same shit on Android though)