I’ve already setup the ssh key, but VSCode keeps asking for password

It was a problem with the config file.
The VSCode needs the “absolute” path.

In case of MacOS, ssh-copy-id seems to only copy the absolute path relative to the user.
In other words, it omits “/Users/username” before “/.ssh“.

Adding “/Users/username” in the IdentityFile attribute in .ssh/config solved the problem.