ISP detection accuracy issues?

Hey everyone, We've been running our web tool, 'What is My ISP? - Find Your Internet Service Provider', for a while now, and it's generally been super useful for our users. However, lately, we've started noticing some pretty inconsistent results, which is a bit of a pain point. The main problem we're facing is with ISP detection accuracy. It's particularly tricky with certain mobile network IPs and smaller regional ISPs. Sometimes, even when users are behind specific VPNs or proxies, our tool fails to identify the actual ISP. Instead, it often returns a generic datacenter provider like 'Cloudflare Inc.' or 'Amazon Technologies Inc.', or even an entirely incorrect regional ISP. This really impacts the reliability of our tool and, more importantly, user trust in our IP geolocation data. We're seeing outputs like this, which aren't ideal:

IP Address: 8.8.8.8
Detected ISP: Google LLC
Expected ISP (from user reports): T-Mobile USA
Confidence Score: 65% (too low)

So, I'm wondering what the best practices are for improving ISP identification accuracy, especially for those challenging mobile networks and regional providers. Are there any reliable APIs or data sources you'd recommend? Also, how do you all handle the complexities of VPNs and proxies when trying to get accurate ISP data? Thanks in advance for any insights!