Earlier quoted context omitted.
No, but.... The above error was from my office. When connecting to ProtonVPN's website via a VPN, there is no error. Seems like it could be a certificate configuration error with the network I'm using, which is odd because it's a University and I've not seen that error anywhere else I regularly visit.
>No, but.... The above error was from my office So.. IT that manages the certs and the gateway, use a MIMT 'attack' to decrypt all your traffic, scan/read it, and then encrypt it again to send it out to the wilderness of the Internet. This is what the browser is messaging. Notifying you that "something is wrong with the connection. Browser is not sure what exactly, thus pointing the finger on the certificate. Perhaps…
Yup, typically referred to as "SSL Inspection" by the companies that produce products to monitor SSL traffic. Normally this is accompanied by controlling the clients and pushing a cert into their browser to avoid the warning messages.