How is it possible that all ports can be opened using vpn to scan using Nmap tool?

So I watched a playlist of Nmap on Hackersploit youtube channel .I practiced all the skills and they all worked fine as in, I had similar results. But everything changed when i used a vpn to change my ip address and scanned again. The result i had was totally different that is, I had all ports opened. Please can someone tell me how that could happen or is it a vulnerability? Thank you in advance @HackerSploit