After updating to 1.18.12 (in-game, PS4 says 2.39), every one of my villagers reverted to novice level and completely changed their trades. I've already changed them into zombie villagers and cured them, so I went from (for example) 1 emerald for 1 mending book, to 10 emeralds for 1 nametag.
If that weren't enough, most have some experience towards the next level, so they won't change trades once I break and replace their workstations (lecterns in this case).
So basically, I have to kill them all, and start from scratch to replace what I had just a couple of days ago, which took many, many hours to do in the first place.