How to restrict access to a specific TEAMS site for external users

Hi,

You could look into labelling the sites like I am showing in this blog?

https://call4cloud.nl/2020/08/the-fellowship-of-group-labeling/

Or maybe looking at this blog from the itpros

https://office365itpros.com/2020/12/09/sensitivity-labels-control-external-sharing-sharepoint-online-sites/