“Sometimes even intentional changes were made. Jeremiah 8:8 says that in Jeremiah’s time the commonly accepted copies of the law of Moses were so incorrect as to contain substantial falsehoods: Jeremiah’s words seem to mean that the false matter had been willfully put in; and it would be hard to prove that our copies of the law are not made from the ones that were commonly accepted in Jeremiah’s time.” Byngton, S. J. (1972). The Bible in Living English. Brooklyn, New York: Watchtower Bible and Tract Society of New York, Inc. p. 9

Dr. James Smith (A Christian Biblical scholar) comments on Jeremiah 8:8:

“Among the wise men, the scribes were singled out for special comment. The scribes were men who could write. The pen (‘et) was probably made from a reed. The scribes in Jeremiah’s day were as corrupt as the priests and the prophets. Somehow through their writings they were attempting to nullify the written word of God. Perhaps they were publishing the false teaching of the prophets and priests… Some have proposed that these scribes were even guilty of altering the very text of the word of God. Whatever they were doing these perverse scribes were distorting the truth.” Smith, J. E. (1972). Jeremiah: A Christian Interpretation. College Press. p. 136

Bill Bright (Christian Scholar) agrees that Jeremiah 8:8 is talking about corruption:

“8:8 Literally translated, ‘The lying pen of the scribes has made it into a lie.” Scribes (sometimes translated “secretaries”) were not responsible to interpret or teach the ;aw until postexilic times (Ezra 7:11). In Jeremiah’s day, scribes primarily wrote and transcribed documents (Jeremiah 36:32). Teaching was the work of priests (Deuteronomy 33:10) and was done orally. Therefore, this verse could be understood to mean that the scribes had purposefully made inaccurate copies of the scrolls containing God’s law. Because the people were taught from these corrupted scrolls, they believed lies rather than truth.” Bright, B. (2007). The Discover God Study Bible NLT. Illinois: Tyndale House Publishers.