I wouldn't even know where to begin, because the slide in quality has permeated every aspect of the operating system, from stability to design. Numerous networking bugs, SSH agent bugs, sleep state bugs, sometimes having to restart my machine because the network screws up so badly, Bluetooth issues that they keep introducing and then not fixing; I have peripherals that just no longer work due to this. I could go on and on. I could talk about the mobilization of a desktop interface (same mistake the Unity and GNOME teams made)

And I don't feel like beating a very dead horse, so just google "macOS Tahoe design issues" and take your pick.