Bible translator Steven Byngton in his book ‘The Bible in Living English’:

“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

“Cheifly, in both O.T. and N.T., a professional student and interpreter of the law of Moses. The scribes were at first priests who made copies of the law. They came to be of importance during the exile, when they were probably responsible for the collecting and copying of the writings that resulted in many of the O.T. books.“Smith, B. (1965). Young People’s Bible Dictionary. Philadelphia: The Westminster Press.

Commenting on Jeremiah 8:8, Reverend David Bauscher writes:

“A very egregious example of probable deliberate alteration can be found in the Massoretic Hebrew of Jeremiah.” Bauscher, D. (2015). The Aramaic-English Interlinear Peshitta Old Testament (The Major Prophets). Australia: Lulu Publishing. p. 8

Lo and behold, the English Standard Version Study Bible (Winner of the prestigious Christian Book Award) agrees with Bauscher and Avalos as well:

“JEREMIAH – NOTE ON 8:8 The Judeans possess God’s law, just as they possess the temple, But their scribes, the professional copiers and teachers of the Scriptures, have altered God’s word to fit their own desires. Thus, they have made it into a lie. JEREMIAH – NOTE ON 8:9 These so-called wise men will be put to shame (2:26; 6:15) because of their changing of God’s word. Rejecting God’s word proves they are really unwise.” C. John Collins, Thomas R. Schreiner, Lane T. Dennis et al. (Eds.). (2008). ESV Study Bible. Crossway.

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

David Carr, Professor of Old Testament and Hebrew and Bible Union Theological Seminary shares Smith’s view in his commentary on Jeremiah 8:8.

“…the vigorous attack on those who claim to be “wise” and that the “Torah is with [them]” when the Torah has been corrupted by the “lying pen of the scribes” (t sheqer sopherim, Jer. 8:8…In addition, both Isaiah and Jeremiah traditions feature broad indictments of groups using writing to oppress the poor (Isa 10:1-2) or corrupt the Torah of God (Jer 8:8).” Carr, D. M. (2005). Writing on the Tablet of the Heart: Origins of Scripture and Literature. New York: Oxford University Press. p. 118

Commenting on Jeremiah 8:8, Biblical scholar and historian Stuart Weeks writes:

“In Jer. 88f. the prophet asks:
How is it that you say, ‘Wise are we, and torah of Yahweh is with us’? yet, behold, into falsehood has the false pen of the scribes turn it into. Wise men will be shamed, shattered, and taken; behold, they reject the word of Yahweh, and what wisdom is there in them?”

The prophet’s hearers, then, are claiming to be wise and to possess the torah of Yahweh; the prophet protests that this torah has been corrupted by the scribes, and prophesies that those who call themselves wise will be destroyed, since they are in fact rejecting the divine word, and their wisdom is therefore unreal.” Weeks, S. (1994). Early Israelite Wisdom: Oxford Theological Monographs. New York: Oxford University Press. pp. 85-86

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.