ما هو تفصيل آراء الفقهاء وأدلتهم بخصوص إدراك المسبوق للركعة إذا كبر تكبيرة الإحرام والإمام راكع، ثم ركع المسبوق والإمام قائم؟

What was attributed to the esteemed scholar Ibn Baz is incorrect. The correct statement from him is that which aligns with the views of many scholars, and it is the relied-upon position in the Hanbali madhhab, which states that one must bow with the Imam, and it is not a condition to achieve ṭumaʾnīnah (stillness) with him. Rather, it is sufficient to merely attain the bowing position before the Imam raises his head.

Ibn Baz said: "So, whenever one performs the takbīr with the Imam and reaches the bowing position before the Imam raises his head, he has caught the rakʿah, even if he does not say the tasbīḥ until after the Imam has raised his head, due to the generality of his (peace be upon him) saying: 'Whoever catches a rakʿah in the prayer has caught the prayer.' And in another narration: 'Whoever catches the bowing has caught the rakʿah.' And due to the ḥadīth of Abu Bakra al-Thaqafi."

He also said: "If the maʾmūm (follower) catches the Imam while he is bowing, the rakʿah is sufficient for him, even if the maʾmūm does not say the tasbīḥ until after the Imam raises his head, due to the generality of the Prophet's (peace be upon him) saying: 'Whoever catches a rakʿah of the prayer has caught the prayer.'"

This is the correct and relied-upon position among the Hanbalis and the majority of scholars. Ibn al-Arabi and others have reported a consensus on it, that catching the rakʿah is by catching the bowing, meaning that he and his Imam meet at the minimum limit of bowing.