Is the communal Dhikr before the Eid prayer an innovation (Bid'ah) or is it legislated (Mashroo’)? And if it is an innovation, should one leave the prayer area until the prayer begins?

Takbir (the pronouncement of "Allahu Akbar") on Eid is a prescribed Sunnah (prophetic tradition), and it is an act of worship in which one must adhere strictly to what has been reported in the Sunnah and the narrations (athar). It is not permissible to innovate in its manner. Scholars have issued fatwas (religious rulings) stating that congregational takbir is an innovation (bid'ah), because it is an innovation in the essence and manner of the worship. It falls under the saying of the Prophet, peace and blessings be upon him: "Whoever introduces into this matter of ours that which is not from it, it is rejected." The prescribed takbir is for each Muslim to perform it individually, raising their voice. As for congregational takbir in one voice, it is an innovation that has no basis in Islamic law.