As others have said, definitely seems like a port forwarding issue. If you’re still trying to solve this, what do your port forward rules look like on your router?
Connect with your phone and check your public ip address (you can do this by googling or using a site like WhatIsMyIP. It should show the same IP as if you were on your home network without the vpn connected.
If that’s working you could try actually connecting to the minecraft server. It might be set up to not respond to pings. You’ll want to use the same IP to connect to it as you’d use if you were on the same network