It doesn’t. It is designed to break SBMM so high skilled players aren’t constantly against other very high skill players, making it more randomised. As their is less high skill players than low skill they get a better chance to get so called “bot lobbies”. It’s explained on their site
“So, what does No Lag VPN do, exactly? It uses the OpenVPN connection protocol and SmartDNS to send your game-related traffic via particular locations. This way, you'll get access to the best lobbies. For example, the NoLag VPN provider is dedicated only to supporting Warzone players and routes.”