It depends,
If the designers where aware of the fact that the villagers could get stuck in the well and wanted this to be the effect than this would not be seen as u bug.
If however the designers where unaware that the villagers would get stuck in this way than this would be an unwanted side effect of the design, and i am under the impression that thats a bug.
In my village 4 out of the 5 villagers where in the well. meaning 1 night with some hostile mobs would disable the village to repopulate.
I replaced the row of cobblestones with cobblestonewall to solve the problem, as villagers can't jump over.
I noticed this to, and then placed my composter 1 block away. but after a some time I noticed that this had not helped in preventing the farmland to be trampled. as 2 of the closest farmland blocks had been trampled.
Although it might have been the Iron golems, as they seem to like that area of farmland and there are 3 of them constantly in that area.
also happens in 1.14.3
seed: 3109806141950473819
coordinates around
X: -4055
Y: -3589
there are several small trees with only 1 jungle logs, that have oak leaves.
(i went there to get jungle saplings, and was surprised to get oak saplings, while i only had jungle logs in my inventory)
I also tested this seed in 1.14.4 (by re-creating a new creative version of my world in 1.14.4) and there the same happens.