git help restore says:
The command can also be used to restore the content in the index with --staged, or restore both the working tree and the index with --staged --worktree.
However, this doesn't seem to work as advertised:
$ mkdir foo; cd foo; git init
$ touch a b; git add a b && git commit -m "Initial commit"
$ echo "Foo" > a; echo "Bar" > b
$ git add a
$ git status --short
M a
M b
$ git restore --staged --worktree .
$ git status --short
M aI'm not sure whether I expect 'a' to be empty at the end of this sequence, but I definitely expect it not to contain staged changes.