لَمْ يَكُنِ ٱلَّذِينَ كَفَرُوا۟ مِنْ أَهْلِ ٱلْكِتَـٰبِ وَٱلْمُشْرِكِينَ مُنفَكِّينَ … What is the grammatical role of مُنفَكِّينَ?

Surah Al-Bayyinah — Part 1

• Accusative predicate of يَكُنِ
• Subject of كَفَرُوا۟
• Genitive complement
• Direct object