This might be related to below commit : 

commit d2a8e69c2c605fbaa3656a5f99aa8d295f74c80e
Author: Inada Naoki <songofacandy@gmail.com>
Date:   Tue Apr 13 13:51:49 2021 +0900

    bpo-43787: Add __iter__ to GzipFile, BZ2File, and LZMAFile (GH-25353)


python -m gzip README.rst
(myenv) ➜  cpython git:(main) ✗ git checkout d2a8e69c2c605fbaa3656a5f99aa8d295f74c80e~1 Lib/gzip.py
Updated 1 path from 2ea7c00ab4
(myenv) ➜  cpython git:(main) ✗ ./python
Python 3.11.0a1+ (heads/main:160c38df7f, Oct 15 2021, 11:25:16) [GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gzip
>>> len([None for _ in gzip.GzipFile("README.rst.gz")])
267
>>> 
(myenv) ➜  cpython git:(main) ✗ git checkout d2a8e69c2c605fbaa3656a5f99aa8d295f74c80e Lib/gzip.py 
Updated 1 path from 1f9874eec6
(myenv) ➜  cpython git:(main) ✗ ./python
Python 3.11.0a1+ (heads/main:160c38df7f, Oct 15 2021, 11:25:16) [GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import gzip
>>> len([None for _ in gzip.GzipFile("README.rst.gz")])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <listcomp>
ValueError: readline of closed file