I can’t speak for what data points Google uses for tracking, however... with JavaScript, there is a plethora of information that can be used to uniquely identify you across IPs, and even across browsers. [0]
If you’re logged in to a service on multiple devices you have now linked multiple fingerprints to your account that can be compared against third party data.
A VPN will not protect you from this tracking.
(I’ve plugged this site before, so I feel like I should say I am not affiliated with it)