This question already has an answer here:
Stack Exchange relies on jQuery to provide some essential functionalities, such as Log In.
Currently, the reference is to Google APIs.
Although the availability of Google APIs is high, the accessibility may vary between different areas in the world.
I suggest add a secondary reference, such as the reference from Microsoft, when Google APIs is not accessible.
The issue turns out to be more severe. If I want to log in to Stack Exchange, I have to go to my office.