I made an account just to comment that we're having the same issues with our Chromebooks. Also started after updating to ChromeOS 102. (from 98).
I tried updating to beta 103 and had the same results.
To give some extra details:
-The window cannot be moved, dragged, or closed
-No keyboard shortcuts work to manipulate this window.
-Blindly typing my username/password is the only way past this screen.
-The issue only happens in a pre-login situation. Un-enrolled devices are able to log into their accounts first and have a fully usable browser to log into the firewall with.
-Powerwash doesn't help.
My next step is to try rolling the Chromebook back to older versions and determine which version the issue first started on.
Edit: I can confirm that the issue does not happen on 98 or 101. The issue does exist on 102 and beta103.
I'm restricting ChromeOS updates to 101 until the issue is resolved and rolling back the few devices that have updated to 101 via USB.
