Microsoft is notorious for asking users to log in multiple times, even when you check “Keep me signed in”.

Now we have the opposite problem. Here I am in Office 365, logged in as the admin user:

I need a break and want to stay secure, so I drop-down the menu top right and choose Sign out:

Lo, I am still signed in:

And no, it is not just a browser cache issue or similar. You can still do administrative tasks.

I have seen references to the bug in Microsoft support forums, so it is known, but unfixed for ages.

I do not publicise this sort of stuff because of any antipathy towards Microsoft. Rather, I do it because it needs to be improved.