Think of Google as a set of signals.

Every time you search, you're sending it a signal that you're interested in a subject.

Google Analytics is embedded in lots of sites. Each time you visit, it sends them back a signal. If you click on one of the ads on the google site, or on any of the millions of sites with embedded google ads, it sends back a signal. If you use Android, each time you change location, make a call, or click on an app, that's a signal.

When using Nest, or Google Home, or Assistant, that's another signal. If you use Google Maps , Google Auto, shopping, photos, drive, translate, image search, gmail, all the office apps, and Gemini. Bingo, a signal.

If you follow a link in any of the above, shared by someone else. A signal.

You don't need to be logged-in. All is needed is an association of that signal with an 'abstract user' which represents you across many systems, devices, and applications.

You can turn off tracking, or tighten privacy settings, or go private. All they need is a loose combination of factors (aka fingerprint) to match your previous actions with your devices, user accounts, or signals.

When you get on Youtube, you're at the tail end of a massive amount of historical data accumulated over time and attached to you. The algorithm just returns a best prediction of what matches that trail. And what you click on and how much of it you watch or skip. Yup, another signal.

And no, none of us can opt out. The same is true for Facebook/Meta, and any other embeddable service, powered by ads.

You can go private, turn off javascript, use alternate browsers, or go back to a flip-phone. Sorry, it doesn't make a difference. Not any more.