I was working to zombie-fy a couple of villagers and two different things happened. I successfully turned a librarian villager into a zombie and went to cure him. He was dressed as a librarian as a zombie - when he curred he lost his profession even though his linked workstation was near by. I had NOT traded with him yet but he had Efficiency V for 44 emeralds and that's what I wanted to get a discount on. I was about to turn him into a zombie again after he had gotten Unbreaking III for some high number of emeralds. Before I turned him into a zombie, he already lost his profession. Screenshot 2021-10-02_16.10.08.png is the zombie villager that just got cured and lost his profession. The other picture is the same villager again with librarian profession about to be zombiefied with Unbreaking III and he lost his profession before I sent him over to the zombie. All cases I did not leave the area.