Service Appointment is shared with FIELD_SERVICE_Default public group even when Service Territory is assigned

Service Appointments in Salesforce Field Service (SFS) are shared with the FIELD_SERVICE_Default public group when the Service Appointment is scheduled to a Service Resource who does not have a Primary Service Territory Membership active during the scheduled time.

The managed package territory sharing solution shares a Service Appointment — when it is scheduled to a Service Resource — with the relevant Service Territory of the resource. This is based on the Service Territory Member Primary or Relocation records, and it allows personas that manage the resource schedule to view all relevant Service Appointments. If no specific Service Territory Member record exists between the Scheduled Start and Scheduled End times of the Service Appointment, the record is shared with the FIELD_SERVICE_Default public group.