If you specify --remove-all-unused-imports in the args section of .pre-commit.yaml then the hook always passes, even when you have unused imports.

Case study

.pre-commit.yaml

repos:
  - repo: https://github.com/PyCQA/autoflake
    rev: v2.2.1
    hooks:
      - id: autoflake
        args: [--remove-all-unused-imports]

foo.py

import random

print("Does nothing")

Try commiting foo.py and the hook will pass!

If I remove the arg then the hook works as expected.

It works as expected when running from the command line:

$ autoflake --remove-all-unused-imports foo.py
--- original/foo.py
+++ fixed/foo.py
@@ -1,3 +1,2 @@
-import random

 print("Does nothing")