Here are some notes on Abdallāh ibn Masʿūd from wiki.
https://en.wikipedia.org/wiki/Abdull...f_the_Qur.27an
(note I am not claiming these note has the highest credibility)
The main point of these note are to highlight there are already differences in the Quran immediately after the death of Muhammad. See the points re
Alleged criticism of the Qur'an below
Abdallāh ibn Masʿūd (Arabic: عبدالله بن مسعود; c.594-c.653) was a companion of the Islamic prophet Muhammad. He was also known by the kunya Abu Abdulrahman.[1]
He was an early convert to Islam, certainly before 616 and probably before 613.[12]
He worked as a personal servant, taking care of Muhammad’s bedding, toothbrush, sandals and travelling hygiene. “He used to screen him when he bathed and wake him when he slept and walk with him in a wild land.”
Muhammad recognised Abdullah as one of the four foremost experts on the Qur'an.
After the death of Muhammad, Abdullah ibn Masud became the eighth-most prominent transmitter of hadith with a total of 848 narrations.[39] Umar called him “a box full of knowledge”.
Alleged criticism of the Qur'an
Uthman produced a standardised version of the Qur'an in 652. He sent a copy to each province and ordered that all other Qur'anic materials “whether written in fragmentary manuscripts or whole copies,” must be burned.[53]
John Gilchrist in his book Jam' Al-Qur'an cites some reports that indicate the following:
That Abdullah was displeased by the finished product.
That he accused Uthman's scribes of adding three extra suras (1, 113 and 114) that had never been part of the original and of making many other small changes to the text.[54]
That he preached a sermon in which he informed the people of Kufa that Uthman’s standardised Quran was a "deceit": “And whoever deceives like this will bring his deceit on the Day of Resurrection … I like it better to read according to the recitation of him whom I love than that of Zayd ibn Thabit … If I knew anyone to be more conversant with Allah’s Book than I am, I would surely go to him if camels could carry me there.”
When Uthman’s agents came to Kufa to burn all the variants, Abdullah hid his copy from them.[55][56] He justified his own version of the recitation by reminding people: "I recited before AIlah's Messenger more than seventy suras of the Qur'an. His Companions know that I have a better understanding of Allah’s Book than they do; and if I were to know that someone had better understanding than I have, I would have gone to him." It was said that nobody could find fault with Abdullah’s version.[57]
When Uthman was called to account for his mismanagement as Caliph, one of the grievances against him was that he had destroyed variant readings of the Qur'an.[58] Much later, Abdullah ibn Masud's variant readings were discussed on equal terms with the Uthmanic text by al-Farra (d. 207/822).[59]
However, the vast majority of Muslim scholars never accepted these reports due to their weakness as well as many strong reports indicating the exact opposite to be true.
The Qur'an says in 15:87 "We have given thee seven of the oft-repeated (verses) and the great Qur'an." The seven often repeated verses refers to Al-fatihah, the first Surah of the Qur'an, which Abdullah Ibn Masud is alleged to have denied. However, quoting Ibn Jarir al-Tabari, Ibn adh-Dhurays, Ibn al-Munzar and Ibn Mardwiyah, as-Suyuti narrated the following: It is narrated from Abdullah Ibn Masud, regarding the word of Allah, ‘We have given you the seven oft-repeated verses;’ he said, “[It is] Fatihatu al-Kitab.”[60]
In another narration Abdullah ibn Masud was asked as to why he did not write al-Fatihah in his mushaf. He replied, ‘If I were to write it, I would write it before every surah.’ Abu Bakr al-Anbari explains this saying every raka’ah (in prayers) starts with al-Fatihah and then another surah is recited. It is as if Ibn Masud said, ‘I have dropped it for the sake of brevity and I have trusted its preservation by Muslims (collectively).’[61]
There are also narrations from Abdullah where he explicitly refers to surahs 113 and 114 as surahs, for example: “Excessively recite two surahs. Allah will make you reach higher ranks in the Hereafter because of them. They are al-Mu'awwidhatayn (i.e. al-Falaq and an-Nas/nos. 113 & 114)…”[62]
Also, four qira'at of the Qur'an (Qira'at of Hamzah, 'Aasim, Khalaf, Al-Kisa'i) have chains of transmission (isnad) going through Abdullah ibn Masud and they all include the above 3 surahs. These are mutawatir chains and thus Islamic scholars give precedence to them, disregarding much weaker chains that go against it as inauthentic.[63]
Due to the above, Islamic scholars rejected the notion of Abdullah ibn Masud rejecting surahs. An-Nawawi says “The Muslims have all agreed that al-Mu'awwidhatayn and al-Fatihah are part of the Qur’an and whoever denies this becomes a disbeliever and whatever is quoted from Ibn Masud in this regard is not true.”[64] Ibn Hazm[65] also rejected the notion of Ibn Masud denying these surahs along with the vast majority of Islamic scholars.
........ end from wiki