Does saying "My Lord, forgive me" (Rabbī ghfir lī) instead of "O Lord, forgive me" (Rabbi ghfir lī) invalidate the prayer due to ignorance of it?

It is recommended for the worshiper to say between the two prostrations: "My Lord, forgive me; My Lord, forgive me," as narrated from Hudhayfah (may Allah be pleased with him). It is permissible to affirm the 'yaa' (ي) in "Rabbī" (ربي), even though it is contrary to what is most common and well-known in Arabic speech. The omission of the 'yaa' and sufficing with the kasra (Rabb) is more prevalent, while affirming the 'yaa' as silent (Rabbī) is less common. All of these are valid linguistic forms.