ANSWER:

You must repeat the whole prayer as you have missed a pillar and that rakah was invalid for missing the fatiha. 

Sheikh, in the first rakah of Zuhr behind the Imam, I forgot to recite the Fateha, and out of ignorance I made Sujood as Sahu. Should I have instead stood up and prayed the first rakah again in this case?

Prayer | June 24, 2022 8:43 am
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While in prayer if by mistake you started reciting something which is not supposed to be recited at that position do you stop as soon as you realize or complete the verse and then stop? For example, reciting Alhamdulillahi Rabbil… but you’re in the sitting position and supposed to recite Attahiyyatu Lillaahil… so should one stop immediately or after completing the verse?