Why is my 'What is my City Name' tool showing inconsistent location accuracy for some users?

hey everyone, i just launched my first web tool, 'What is my City Name', and it's been a fun learning curve! honestly, i'm a total noob at this, so please be patient with my questions. i'm seeing some really strange issues with location accuracy. for some visitors, it's spot on, but for others, it's way off, like showing a city hundreds of miles away from their actual location. it's kinda frustrating 'cause i want it to be reliable.

what factors usually cause these big discrepancies in ip-based geolocation? i'm wondering if specific types of connections, like vpns or mobile hotspots, are just harder to pinpoint accurately. and since i'm on a super tight budget as a beginner, what are some budget-friendly ways to improve the accurracy of my tool? really waiting for an expert reply here, any help would be amazing!