the average residential DHCP-pool-assigned customer on a cablemodem, dsl, gpon line or something doesn't change IP addresses that much, and very often the dhcpd will renew the router/modem's WAN port lease with the same address for months at a time. even if it's not an actual static IP.
this alone can be used to correlate a huge number of things since very often you have one household with a whole assortment of people and tablets, phones, laptops, xboxes, playstations, smart speakers etc all behind one IP address and NAT.
just having an entity like google know that your ip address is coming from a /24 in a /19 sized IP block that's known to be a comcast dhcp pool in a particular city/metro area is a huge amount of info.
other things happen as well. you have other people in your household who installed the facebook app on their phone and left geolocation/GPS permissions set to on? now your IP address has been correlated with a very specific latitude/longitude and the usage patterns of your (spouse, roommate, child, etc) who is using that app.
I'm well aware of the issues with IP (I mentioned that I use a VPN), and the general public is becoming more wary too, as can be seen with the rise of VPN usage. Which is why timing analysis is so scary, it bypasses most countermeasures
this alone can be used to correlate a huge number of things since very often you have one household with a whole assortment of people and tablets, phones, laptops, xboxes, playstations, smart speakers etc all behind one IP address and NAT.
just having an entity like google know that your ip address is coming from a /24 in a /19 sized IP block that's known to be a comcast dhcp pool in a particular city/metro area is a huge amount of info.
other things happen as well. you have other people in your household who installed the facebook app on their phone and left geolocation/GPS permissions set to on? now your IP address has been correlated with a very specific latitude/longitude and the usage patterns of your (spouse, roommate, child, etc) who is using that app.