Distance changes the journey
Traffic travels from your device to a VPN server and then to its destination. A longer route may add latency. Compare nearby locations before assuming the fastest location is the most distant one.
Start with the local network
Test the connection without a VPN and compare it under similar conditions. Wi-Fi interference, a busy router and background transfers can affect both measurements.
Compare like with like
Use the same device, network and test destination. Repeat a test rather than treating a single result as permanent. Avoid changing several settings at once.
Find a useful balance
Pick a stable location that works for your regular activity. Keep your app updated and check available connection options. No provider can promise the same speed across every device and network.