Changing between multiple Microsoft Teams accounts within the app or browser
To ensure I fully understand your situation and provide the most effective assistance, I’ll need a few additional details, such as:
Did the issue start after any recent changes (such as a license update, application deployment, or policy modification)?
Are the affected users internal employees, guest users, or external collaborators?
Are the affected users part of any specific security group or department?
Does this behavior also occur when accessing Teams on the web using an InPrivate/Incognito browser session?
In the meantime, I came across a similar case where the issue appeared to be related to network restrictions. As a troubleshooting step, you could try switching from the corporate network to a personal hotspot or another external network, and then attempt to sign in to Microsoft Teams again to see if this helps
This test may help determine whether the issue is related to network restrictions within the corporate environment. Any update would be appreciated.