As for the interpretation of its name being "the Seven", it is seven verses; there is no disagreement among all the reciters and scholars regarding that.

They only differed regarding the verses by which it became seven verses. Most of the people of Kūfa said: It became seven verses with ﴿In the name of Allah, the Entirely Merciful, the Especially Merciful﴾, and that has been narrated from a group of the Companions of the Messenger of Allah Peace and blessings of God be upon him and the Successors. Others said: They are seven verses, but ﴿In the name of Allah, the Entirely Merciful, the Especially Merciful﴾ is not among them; rather, the seventh is "anʿamta ʿalayhim" [whom You have blessed]. That is the statement of the majority of the reciters of the people of Medina and their master scholars (1).

Abū Jaʿfar said: We have explained the correct view according to us regarding that in our book, al-Laṭīf fī Aḥkām Sharāʾiʿ al-Islām, with concise words, and we shall exhaustively clarify that by citing the statements of those who disagreed about it among the Companions, the Successors, the earlier ones, and the later ones in our book, al-Akbar fī Aḥkām Sharāʾiʿ al-Islām, if Allah wills.

As for the Prophet's Peace and blessings of God be upon him description of its seven verses as being mathānī (oft-repeated), it is because its recitation is repeated (tuthnā) in every prayer, voluntary and obligatory. Likewise was al-Ḥasan al-Baṣrī interpreting that.

135- Yaʿqūb ibn Ibrāhīm narrated to me, he said: Ibn ʿUlayya narrated to us, from Abū Rajāʾ, he said: I asked al-Ḥasan about His statement: ﴿And We have certainly given you seven of the oft-repeated [verses] and the great Qur'an﴾