B603 false positive?

Describe the bug
I don't understand how I should "check for untrusted input.

To Reproduce
Steps to reproduce the behavior:

With the code:

import shlex
import subprocess

def foo():
    args = shlex.split("git rev-parse HEAD")
    return str(subprocess.check_output(args, shell=False), "utf-8").strip()

Gives Issue: [B603:subprocess_without_shell_equals_true] subprocess call - check for execution of untrusted input. I don't understand how this is shell equals true given that "shell=False" is passed, nor how this is untrusted input.

Expected behavior

This line shouldn't be flagged as a warning

Bandit version

bandit --version
bandit 1.4.0

Additional context

Reproduce the B603 warning with the Python snippet using shlex.split and subprocess.check_output(..., shell=False) under Bandit 1.4.0. Start by tracing the B603 check and its handling of shell=False and input trust. Done means the reported example no longer produces a warning, with regression coverage for the expected behavior.