[vbsteven]

> I do most searches in an incognito window so it can't be browser history.

Incognito mode is mostly a convenience for you to do browsing without saving local history or cookies. It doesn't stop tracking.

I assume the fingerprint is different in incognito versus a regular window. But unless you are using VPN/adblockers/pihole/etc your browser is still executing third party JS and potentially sending tracking data to google using a plain https connection coming from your residential IP.

I can imagine it's not that hard for Google to link different requests from the same IP with slightly different fingerprint data to be coming from the same user.

edit: and for searches it is even easier, because you are communicating directly with google by performing the search, no tracker or JS necessary.