In the case assignment queue, No virtual team is applied but Agent recommendation is showing the agent list. Explain how?

As per the application design ,when the ticket has been assigned in a Queue where it does not have any agents / virtual teams the application will check for the default team . 

The default team is set from case assignment >> assignment queues. We can add the virtual teams/agents will be recommended from the default team queue.

It will be automatically associated with queues where no individual agents or virtual teams have been added. Unless you specify in every queue, this default team will be utilised if you enable auto-assignment.