Ratty "network activity including emails and browsing activity is visible to IT admins."
This message is a default notice from Android and is related to the context of VPNs used in enterprise networks, where a business may require you to use VPN to access their internal network. In the case of a VPN that logs data or is an enterprise one like this, yes, they could see activity.
For commercial VPN services this is irrelevant, unless they actually can see that data, of course.