When I do SPC g s, I get something that looks like
^[[1mdiff src/main.rs^[[m
Pretty much every line has some ^[[ escape sequence.
I'm running inside iterm on mac. I've tried searching, but I haven't found anyone with the same problem. It seems like its trying to bold the text, but it can't. I don't know if this problem is because of spacemacs or because of iterm.
The problem was not with spacemacs or iterm, but actually with git. For ~/.gitconfig, under color, change ui = always to ui = auto.