This has nothing to do with pop-os. If you don’t like this window behavior, take it up with Proton.

Not that it’s even a real problem. If you enlarge a login window, it’s not going to add any content to the window. Why would you even want your VPN client taking up half your screen anyway? You log in, you turn it on, you turn it off. That’s basically it…

Don’t tile Proton VPN window, let it float