DuckDuckGo measured Google's "filter bubble" problem:
https://spreadprivacy.com/google-filter-bubble-study/
– most participants saw results unique to them
– Google included links for some participants that it did not include for others, even when logged out and in private browsing mode
– results within the news and videos infoboxes also varied significantly
– private browsing mode and being logged out of Google offered very little filter bubble protection