I have a scenario with Sitecore 9.2 where CM users are getting the "too many users" message when they try to log in. I've gone in there as a global admin to kick users (since regular users can't), and I've found the slots are taken up by sitecore\anonymous users. I believe the client does browse the site on the CM sometimes, but that would be against the web database, and there's no end-user login on this site. So it seems very odd that an anonymous account can eat a CM login slot. Has anyone encountered this and have a solution? (I do have a Sitecore ticket on this as well, if they come back with a solution I'll provide it to everyone.)
I have tried to reproduce the issue on my Sitecore 9.3 instance. And when I access the KickUser admin page (https://Your_Instance_url/sitecore/client/Applications/LicenseOptions/KickUser), this is what I can see:
It appears the Kick Off user page is wrongly showing the logged in users as Sitecore\Anonymous - which could be an issue we can follow up with Sitecore. In my case, I have two valid Sitecore users logged in (and not Anonymous users)
So basically what you are seeing as Anonymous users are actually valid CMS users. Please verify.
Update Sitecore have confirmed this is a bug and provided the reference number 364166. More information about public reference numbers can be found here