The comment you mention applies to source code encoding and it's obsolete for Python 3 since the beginning. This is about something else: https://docs.python.org/3.15/whatsnew/3.15.html#whatsnew315-...

Makes sense, my bad, but even that is something I've never seen. I guess this is mostly a Windows thing? I've luckily never had the misfortune of having to deploy Python code on Windows.