Bihar al-Anwar (Arabic: بِحَار ٱلْأَنْوَار, meaning "Seas of Lights") is a comprehensive collection of traditions (ahadith) compiled by Shia scholar Mohammad-Baqer Majlesi (d. 1110/1698), known as Allama Majlisi.
There are some hadith along those lines. It has been suggested that these are forged hadith. In some cases, when the ayah is presented differently, with insertions, it has been suggested that this may have been an explanation or gloss by the speaker which was later misunderstood as a quotation of the entire ayah.
It is true that there are a few hadith along these lines both in Sunni and Shi'i texts.
Quran is intact with out any distortion whatsoever. There are narrations in Sunni books like Bukhari, Muslim, Al-Tirmithi, Al-Nasaa'ee, Ibn Maajah, Muwatta' Malik, Musnad Ibn Hanbal and other well known books claiming stories about distortion in some Suras of Quran. Our authentic evidence that Quran is intact, made our leading Ulama reject any narration contradicts with the fact that Quran is intact even if it the narration is mentioned in a Shia book. Such narrations in Shia books are much less than in Sunni books and some of them were copied from Sunni books. Such narrations are either fabricated or misunderstood.
Bukhari in Hadeeth number 4608 narrated from Umar ibn al-Khattab different words in Quran which never recited by the Prophet Muhammad (SAWA). Bukhari narrated in Hadeeth number 6327 and 6328 from Umar ibn al-Khattab a claimed verse on stoning the old man and old woman. Such verse is not in Quran but Umar said it is. These are just few examples of long list of such rejected Sunni narrations on this matter.
'The fact which we believe in according to most authentic evidence from Ahlul Bayt (AS) is: Quran is intact and preserved and protected by Allah (SWT) from distortion.
Thank you for your question. Different authors had different purposes and differing criteria when compiling their books. Sometimes, it is not the author's criteria, but the version of the book that has reached us that may be problematic, as Shii hadith history is a history of textual transmission.
Bihar al-anwar is a book that was written in the 17th Century which tried to preserve as much of the Shii tradition as possible. The author was therefore not concerned with sifting reports and left that to later hadith scholars, as hadith scholars also use different criteria when analyzing the reports in various books.
Usul al-Kafi on the other hand was an attempt to produce a book of reliable reports, but at the same time, not everybody agrees with what the author of al-Kafi (al-Kulayni) considered reliable. In short, hadith scholarship is a complex field where there are many aspects to weigh up and that is why it takes expertise. The natural outcome of that is that not everyone will agree with a specific scholar's assessment if they are trying to produce a reliable work.
May you always be successful