Does the prayer become void if the congregant, after missing one rak'ah in a four-rak'ah prayer, prostrates for the fourth rak'ah immediately after reciting Al-Fatihah without bowing?

Ruku' (bowing) is a pillar (Rukn) without which prayer is invalid if omitted intentionally. So, whoever intentionally omits it while capable of performing it, their prayer is nullified, and they must repeat it. As for whoever omits it out of forgetfulness, they must return to perform it and what comes after it, then perform the two prostrations of forgetfulness (Sujud al-Sahw), whether they are still in the prayer or if a long time has not passed since its conclusion.