The sender is in the workspace but has no licensed seat, so Account Protection blocks sends.
No seat is a badge, not a status. Status is still Draft, Connecting, Challenge required, Active, Limited, Paused, Error, or Needs login. The extra sender stays. It does not send until Owner or admin deletes a sender or chooses a plan with more seats on Settings → Billing.
Members can see the badge. Only Owner or admin can change seats.