Villagers run in circles under Y=40 and find the safest route over it

so I made an underground village on my ps4 bedrock, and once I reached y=40, I realized some villagers started exiting their homes all the time to higher ground.

I looked all over there were no caves and no water holes. I made sure that there wasn't a single dark block in a 100 block radius, yet the villagers won't stop

I experimented with this and found out that any villager under y=40 gets extremely uncomfortable and runs fast as if it's raining.

I'm not sure whether this is implemented in the game on purpose or a bug but it's annoying

thank you for your time