It's REALLY easy to check what the browser is doing and multiple people have. There was an article floating around claiming it phones home but many people very quickly pointed out that the author was mistaken, at best (they thought some CSS or something completely normal being loaded in the background was brave "phoning home").
The question is not what the browser is doing (which is easily verifiable with a network proxy, even without the browser being open source), but the question is what the server is doing with the data that is being sent to it by the browser, and that data includes PII like the IP address.
The best way to remove this question is for browsers to be zero-telemetry which is what I was advocating for.
