our 'what is my ip address' tool getting weird public IP discrepancies for mobile users

hey folks, we've been running our what is my ip address tool for a while now, and generally, it's pretty solid. it's become a decent little public IP checker for our users. but lately, we're seeing some really strange behavior, especially for a subset of our mobile users.

the public IP address shown for them is often completely off, like, not even close to their actual location. this is leading to totally incorrect geo-location data, which is a real pain. oddly, this isn't happening for desktop users at all, only mobile. it's like their true IP is being masked or routed weirdly. here’s a dummy example of what we sometimes see in our logs:

User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148
Reported IP: 104.28.232.121
Geo-Location (Reported IP): San Francisco, CA, USA
Expected Geo-Location (from user feedback): Berlin, Germany
ISP for Reported IP: Cloudflare, Inc.

is this a common issue with mobile networks, proxies, or specific carrier setups that might obscure the true public IP address? what's the best or most reliable way to get the actual user's IP when they're on a mobile network, especialy given how many things can proxy traffic now? we're looking for any insights or debugging tips you guys might have. thanks in advance!