Yes. You raise a good point that fir some people the connection might make a difference.
But this doesn’t explain how a person with a strong and consistently good internet might have a different blitz and bullet rating.
Because there are a combination of factors, technical, human, environmental, relational, physical that all combine. I theorise that more of these come relatively into play when using short time controls.
Different pool, different rating. Always.
Of course. But the question is why?