Of course you're dealing with your local licensing authority, but they'll all have a rule substantially the same as the model rule cited.
California's state bar even has a formal opinion calling out this or similar behavior:
"Had Seller’s Attorney intentionally created a defective “redline” to surreptitiously conceal the change to the
covenant not to compete, his conduct would constitute deceit, active concealment and possibly fraud, in
violation of Seller’s Attorney’s ethical obligations."
California's state bar even has a formal opinion calling out this or similar behavior:
"Had Seller’s Attorney intentionally created a defective “redline” to surreptitiously conceal the change to the covenant not to compete, his conduct would constitute deceit, active concealment and possibly fraud, in violation of Seller’s Attorney’s ethical obligations."
[https://www.calbar.ca.gov/Portals/0/documents/ethics/Opinion...]