Weird-ness, I have a Windows Teams Client that previously had added another Teams account, from another tenant. This was released recently, that a work user could add another work account from another tenant to their desktop client (or more than one).
Of course, the ability to add a “personal” account (like live.com) and one other work / school account, has been around since February 2021 – https://www.microsoft.com/en-ww/microsoft-365/roadmap?filters=&searchterms=68845.
So, now the client shows two accounts on the menu dropdown in Teams.

That means that two work accounts have been added to this profile in the Teams client. The ability to add more there as well. As well as a “personal” account.
I saw an issue, where the user was added to another tenants Team Teams, and that profile appeared in the users Teams client. That was ok… BUT when they tried to remove the new guest user from their Teams client, they couldn’t. Even though the guest account had been removed from the other tenant.
So… that resulted in this MS roadmap entry – https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=88430.
That is this:

So, the ability to show and hide the guest tenant from the Teams list is ongoing (as of the date of this blog, check out the three squares at the top left of the item).
I’ve also had success with the newest version of Teams that has been released (1.5.00.2164) with the guest account being removed automatically, when the guest account on the other tenant has been removed by that tenant admin group.
But I’ve had an issue with a Teams install that doesn’t obey the rules. The guest account was disabled and removed by the guest tenant administrator group. BUT the guest account didn’t disappear with the recent release (1.5.00.2164).
Looking at the logs.txt in the desktop folder in the Teams logs (https://docs.microsoft.com/en-us/microsoftteams/log-files); I saw this:
<dates and stuff were removed> <10892> -- info -- [AppStateService] [EnableBlueberry] enableBlueberry is defined as true returning : true
<dates and stuff were removed> <10892> -- info -- [DesktopConfig] Get SignedInActiveUser. Type: "AAD"
<dates and stuff were removed> <10892> -- info -- [AppStateService] [EnableBlueberry] enableBlueberry is defined as true returning : true
<dates and stuff were removed> <10892> -- info -- [DesktopConfig] Get SignedInActiveUser: false with accountType: AAD
<dates and stuff were removed> <10892> -- info -- [DesktopConfig] Could not Get SignedInActiveUser user via property, fallback to map.
This looks like the check is being made for the guest account on the client. But then the user isn’t getting the guest account removed. It does look like an AAD issue.
So currently, I think we’d better wait for an update to be rolled out across the Teams clients and the roadmap change be fully deployed.