Why does bool of an environment variable set to false evaluate to True?

Environment values are strings. In Python every nonempty string, including "false" and "0", is truthy. Parse a documented set such as {"true", "1"} and {"false", "0"} after normalizing case and surrounding whitespace. Reject unknown values rather than silently enabling a sensitive feature. Test missing, empty, mixed-case and misspelled values. Keep the default explicit and appropriate to the feature: debugging and public access should not be enabled by an accidental fallback. The parsing rule must be shared between local development, containers and production so the same configuration has the same meaning everywhere. Minimal example:

def parse_flag(text):
    value = text.strip().lower()
    if value in {"true", "1"}:
        return True
    if value in {"false", "0"}:
        return False
    raise ValueError("Unknown boolean setting")

assert parse_flag(" FALSE ") is False
assert parse_flag("1") is True
try:
    parse_flag("flase")
except ValueError:
    pass
else:
    raise AssertionError("Typo was accepted")