Your postal address is displayed right there at the top of the page when you’re signed in and looking at the “dashboard,” so it’s readily available bold as brass for anyone to scrape. The real question is, why was third party code even allowed to be served with that page? What possible benefit could it serve the user to have Meta and LinkedIn tracking pixels on their postal mail dashboard?
That was a rhetorical question. The answer is money, and how much of it those social media/tech companies were paying the Postal Service to allow them to do it – end user be damned. The notion that the USPS was “unaware” of this reeks so bad that you could smell it from space.