Minecraft – How are unemployed villagers claiming job site blocks claimed by other traded villagers

I've been struggling with building my own village for some time now and I've come to observe several phenomena that seem to contradict the official Minecraft wiki. In particular, I am witnessing villagers relinquishing their job site blocks for no apparent reason.

Here's my setup: Every villager of mine is within a 3×2 small "house", which contains its job site blocks plus a bed. Initially, I left a 1×1 opening in one of the walls so I could trade with the villager without having to open the iron door. This village is at least 300 blocks away from my main base where I might have some unaccounted for composters or stonecutters.

I have a single brewing stand in the village. I am 100% positive in that. And I have a single cleric that claimed that job site block after which I locked him into that house. So far so good. I've traded with that villager countless times and it has restocked its supply which confirms that he had claimed exactly the block I am talking about (as he is enclosed in the mentioned 2×3 "house", there is no way he could restock from a different brewing stand, even if there was one, which there wasn't.

I released 2 librarians from their houses so they can breed and multiply. I built several empty houses with beds, fed the 2 librarians, and sure enough, soon, I have several unemployed villagers running about. What happens next is completely baffling. I observe that one of the unemployed villagers is a novice cleric. A cleric? I have a single brewing stand which is claimed by the master cleric.

I go and trade with the master cleric and he can't restock meaning the novice has somehow claimed the job site block which had already been claimed. I had observed similar behavior a while ago, when all my villagers were roaming freely in a 40×40 hall. I had thought back then that perhaps for some reason my master villager went a little far away and for some reason was not able to pathfind or whatever to his job site and so relinquished it. But in this case he had nowhere to go. He was in his 2×3 house all the time next to his bed and job site block.

I kept observing this behavior until I decided to shut down the 1×1 opening in the wall of the houses. After that I don't seem to observe this behavior any more.

So, how come a villager that is forced to stand by a job site block it has claimed, ends up relinquishing it in favor of an unemployed villager if there is a 1×1 opening in the wall that no one can get in or out of?

I am playing Minecraft 1.14.4 Java edition, survival mode.

Has anyone observed similar behavior and how do you reconcile it with the following words from the official minecraft wiki:

When the block is claimed, [its owner emits green particles‌[Bedrock Edition only]] and no other villager can claim it unless the owner relinquishes it.