What is the central legal-theoretical question raised by the reported word mutatābiʿāt from Ibn Masʿūd?

The Four Proofs: Fiqh, Uṣūl al-Fiqh and Kalām

• Whether the Qurʾān specifies three fasting days at all
• Whether all transmitted readings have canonical status
• The transmission’s evidentiary authority and its implication for consecutive days
• Whether consecutiveness is proven by universal consensus without supporting evidence