I've started setting up ZSH for VSCode. It worked for a small bit, but then it changed to Git Bash (my previous default shell). I tried changing the shell back to ZSH, but it didn't display in the list of opinions. Though, it does display WSL, which displays a completely different theme
My theme (in windows terminal, unbuntu, ect):

The theme that is in VSCode:

I've tried adding this to my settings.json:
"terminal.integrated.shell.windows": "/bin/zsh",
But it says: "The terminal process failed to launch: Path to shell executable "\bin\zsh" does not exist."
How can I fix this (change the default shell back to ZSH)?
Looks like it has changed slightly on Macs.
Mac - ⌘ + Shift + P
Type "Terminal: Select Default Profile", and select it.
Then you will see this:
Choose bash or whatever, and then you must close and restart VS Code.
open "~/.config/Code/User/settings.json"
add your default shell depending on you OS:
"terminal.integrated.defaultProfile.linux": "zsh"
"terminal.integrated.defaultProfile.osx": "zsh"
"terminal.integrated.defaultProfile.windows": "zsh"
Here's the solution:
terminal.integrated.shell.osx has been deprecated for terminal.integrated.defaultProfile.osx (shell to defaultProfile) but the new rule instead defaults to bash (at the time of this post)
What actually happens is this: (got it by using the GUI instead) - it's the path. terminal.integrated.defaultProfile.osx actually works, but the value has to be changed from /bin/zsh to zsh.
So the setting should be "terminal.integrated.defaultProfile.osx": "zsh" instead of "terminal.integrated.defaultProfile.osx": "/bin/zsh".
Also note the language changed from Default shell to defaultProfile.
Try which zsh to confirm the path of your zsh executable. You might be having path error.
Or Try the GUI way.
Windows - Ctrl + Shift + P
Mac - ⌘ + Shift + P
Terminal: Select Default Shell and select it.It also likely that the zsh installation/configuration error caused your entry in settings.json file to be invalid. Once you have selected the shell, hit ctrl + ~ or ⌘ + J to open the terminal window and see the results. If you already opened a terminal then you would have to trash it or open another one.
You could also open your settings.json and see or add the following entry directly.
// Edit July 2021 - New Updated Snippet
"terminal.integrated.defaultProfile.osx": "zsh"
// Now deprecated
"terminal.integrated.shell.osx": "/bin/zsh"