Query string causes problems

I'm pretty sure you are incorrect that the website is adding the query string. My evidence:

1) I clicked on a bunch of other websites from 1P and all of the URLs have similar query strings added.

2) I instantiated a simple http server and then logged the traffic between the server and the browser. Upon clicking the website from 1P, the first thing the browser sends is:
GET /?pzrzvkahxbcmonppmt5oufpd4u=4iawrmbzojgcjgqkipskdlfj HTTP/1.1

Seems compelling that 1P (or 1P's browser extension) is adding the query string, not the websites.