What is the authenticity of the story of Salman al-Farsi with the Christian monks, their possession of the description of the Prophet (peace be upon him), his meeting with the Prophet (peace be upon him), and the presence of the Seal of Prophethood on his back, and did scholars unanimously agree on its authenticity, or were there those who deemed it weak?

The story of Salman was narrated with chains of transmission, some of which contain issues, yet no one has been found to declare them weak. Al-Hakim narrated it and deemed it authentic, and Al-Albani and Al-Wadi'i improved some of its chains. Al-Haythami said that the narrators of the first narration's chain are the narrators of Sahih except for Muhammad ibn Ishaq, who explicitly stated hearing it, and the narrators of the second narration's chain are the narrators of Sahih except for Amr ibn Abi Qurrah Al-Kindi, who is trustworthy.