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 ba

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." [https://www.calbar.ca.gov/Portals/0/documents/ethics/Opinions/CAL%202013-189%20%5B11-0002%5D%20v.1.pdf https://www.calbar.ca.gov/Portals/0/documents/ethics/Opinion...]