Just happened to me in a local world that allows multiplayer. After an illager patrol that spawned inside the smithy killed off all armourers I respawned the armorers in creative, made sure they traded different pieces of armour and traded with them until they reached master level. That happened Friday.
Saturday morning I loaded the game and looked into the smithy and there were tthree armorers and one librarian although all the reading stands in the village should have been occupied by libarians.
During a raid I had one Illagers that was part of the raid spawn in a house killing the two farmers living and working there. After successfully completing the raid I found more illagers in another house where they killed the four armourers and the two weapon smiths that were living there. All of the villagers were master level.
I ended up putting the world in creative mode and spent several hours to get the villagers back at the level and with the offers they had but I still have a miess with villagers assigning themselves to beds they can't reach and I keep encountering more bugs.
Affected version is 1.14.60
I just had a villager disappear almost right in front of my eyes. I entered a room of a house in my village. There were two librarians behind a counter, workstations and a fence gate so that they could not get out. I went to the settings and opened Feedback on my Android phone, to report another issue that I had encountered (Actually I just copied the URL to my laptop, but I had to register a user and research the issue, so it took me some time)
When I returned to the game one librarian was gone. The librarian was master level. Due to another bug (one of my armorers turned into a librarian some time before) there were more librarians that reading stands im my village. But there are a lot of bookshelves in the librarians room. Affected version is 1.14.60. This is the third issue I have encountered in the past 36 hours and I'm really starting to wonder if this last update was a good idea.
Edit:
I just checked and noticed that one armorer, the librarian that originally was an armorer, a weapon smith and both fletchers (all of them were master level) have disappered as well.