You won't be able to see that activity until after it has happened. An empty network monitor list isn't a guarantee of future behavior. Or current behavior.

Okay. Then solve p=np. Until then, we monitor and reverse engineer to verify as best we can.

It doesn't need to be that hard. A reasonable solution is to quarantine the tab/app. Proactively revoke its network access after its loaded.

> It does not omit future network calls.

It does.

> You can, in fact, use the network tab to monitor a page's ongoing network activity as originally suggested.

Did you forget that this comment chain was about leaking data to the server? Observing that you have leaked (note: past tense!) your data is not a recommended way to prevent leaking data.

>> "It does."

I am sitting here looking at a new entry added from a button click that creates a network call. Either you are wrong or confused about what the discussion is about.

Was the entry added before or after you clicked the button?