Short answer
HubSpot's KB: Delete contact automatically deletes enrolled contacts, for example inactive contacts in bulk. Contacts can be restored within 90 days, and the restore tool can filter by the workflow that deleted them. Turn off that workflow first so restored contacts aren't deleted again.
1. Restore
Restore options on the contacts index in my demo portal.

2. Permanent deletes
GDPR deletions don't go to the recycle bin. See GDPR delete.