This is still the same in 3.11. I added another line to the example's file, which shows more clearly what's happening:

>>> open('x.py', 'wb').write(b'#\x00\na\nb\n')

% ./python.exe x.py
Traceback (most recent call last):
  File "x.py", line 2, in <module>
    a
NameError: name 'b' is not defined