Your experience is not the only possible experience
Not to mention numerous VPN provider who recommend not using NetworkManager, some have even had to write an alternative to get round the bugs (or "working as designed") and other privacy issues like DNS leaking, due to how it manages stuff.
https://airvpn.org/forums/topic/25263-how-to-stop-dns-leaks-in-linux-network-manager/
Biting the hand that feeds IT
