Still getting IP data discrepancy, is it my caching setup?

I'm still pulling my hair out over this IP geolocation accuracy issue. After switching APIs last week, I thought we were finally past the incorrect country data problem, but it just keeps coming back.

The new API works perfectly for a while, giving us the correct IP geolocation for our users. But then, inexplicably, for the exact same IP address, it starts returning the old, incorrect country data again. It's like something is holding onto outdated information and forcing it back into the system. This persistent IP data discrepancy is driving me absolutely insane and affecting our user experience.

Here's a simplified example of what I'm seeing in our logs:

// Initial correct response for a user from the US
console.log('API Response for 192.0.2.1: { country: "United States", code: "US", source: "NewAPI" }');

// Later, for the same IP, an incorrect response (e.g., from an old cache?)
console.log('API Response for 192.0.2.1: { country: "Canada", code: "CA", source: "Unknown" }');

// Even later, sometimes it corrects itself, then reverts again... maddening!
console.log('API Response for 192.0.2.1: { country: "United States", code: "US", source: "NewAPI" }');

I've tried clearing server-side caches, disabling client-side caching headers, and even purging our CDN, but nothing seems to stick. Is there some obscure server-level caching I'm missing? Could it be a DNS caching issue on our end, or perhaps something even deeper with how the new IP geolocation API is being integrated or how its responses are handled upstream before they even reach us? I'm completely at a loss.

Please, any insights or suggestions would be a lifesaver. Thanks in advance!