optimizing ip lookup accuracy for 'what is my city'?

hey folks,

we're currently developing a "What is my City Name" web tool, and the core challenge we're facing is achieving high IP lookup accuracy at the city level. it's been a real headache trying to get consistent results.

the problem is, we're seeing some pretty inconsistent city-level detection, especially with mobile network IPs or certain regional ISPs. our current geo-IP provider sometimes returns much broader regions or even incorrect cities. for example, an IP might resolve to 'State, Country' instead of 'City, State, Country', or even a neighboring city entirely. we've logged these discrepancies a bunch of times:

// Example of a common discrepancy:
// Input IP: 172.x.x.x (known to be 'Springfield, IL')
// Current API Output: {"city": "Chicago", "state": "Illinois", "country": "US"}
// Or sometimes: {"city": null, "state": "Illinois", "country": "US"}

what strategies or advanced geo-IP databases/APIs have you found to significantly improve city-level IP lookup accuracy, particually for these edge cases and mobile data? we're really looking beyond basic GeoLite2 options here.