I was looking into the system’s sync/shutdown/halt user accounts and found this page:

I wanted to reply to the comments I found there so I logged in. Now I can’t see the comments or otherwise interact with the page. I’m using Chrome on Win10-x64 and disabled my ad blocker (uBlock Origin). I tried opening the page in an incognito window, and again I can see the comments while logged out. The same thing happens with Firefox.

(This looks like a handy way to allow those with physical access to shutdown my system in an emergency. The next problem is how to restrict such logins to the console, and not allow them via ssh.)