There are tools such as https://ipapi.is/ that can be used to geolocate any IPv4 and IPv6 address in the world. Sometimes those tools are not extremely accurate, but usually they are accurate to the city level.
I know about geolocation by IP address. But as I mentioned, geolocation based on my previous ISPs IPs were never this fine-grained. What could my current ISP be doing different from these other ISPs?