VPNs create an encrypted connection between your device/computer and the VPN server. No one can track your web activity to you if you use a PS4/PS5 VPN (insert mandatory meme).
While your activity on the internet can be tracked back to the VPN IP addresses and monitored, it cannot be traced back to you. While the VPN connection between your PlayStation and the VPN connection is secure, the VPN connection to the rest of the internet is not.
A PS4/PS5 VPN service can be used for many reasons, including establishing a secure connection over a insecure network, accessing censored content or region-specific web content, hiding Peer2Peer activity and blocking DDOS attacks.