According to the mainstream Sunni position discussed by al-Nawawī, how is deliberate Prophetic fabrication classified?

The Grave Warning Against Lying About the Prophet: Narration, Intent and Critical Duty

• Automatic disbelief without any scholarly difference
• A major sin that does not by itself necessarily entail unbelief
• Always a minor infraction without serious consequence
• Only a technical memory defect, not a moral offense