It is increasingly useless to even use the app because each time I login within seconds I get 5+ bots or foreign accounts claiming close proximity.

I understand that it would be incredibly difficult to try and keep them in check but I offer up two simple solutions. Since VPNs make it hard to accurately track a user location I would first see if their ip address location changes drastically from time to time then make them first pass a ‘r u human’ test the next time they want to send a message. So people using random vpns can still use it but bots will require someone on the front end. Next use device gyroscopic functions to see that the device is in someone’s hands moving regularly before allowing to send a message. Next if a user sends messages to multiple people in less than x number of seconds this is less likely someone who isn’t just spamming everyone.