For me it's the enormous number of (mostly hidden) states that a local repository can be in. That's what gives me anxiety as soon as I go off the golden path: you have to keep a running mental model of where exactly you are (what state the repo is in) in any given ongoing process, and if you don't do the right thing as the next step, you can get into an even worse and more obscure state that you then have to chart your way out of (mostly blindly).
It's like that old saying about democracy: "Git is the worst version-control system, except for all the others."
It's like that old saying about democracy: "Git is the worst version-control system, except for all the others."