Raid ends with 'Raid - defeat' when there are still villagers inhabiting the village

The bug

Raid ends when only one villager is defeated even if there are other villagers in the village.

To reproduce

1. find a village (or make one)
2. find the furthest house from the centre or make a house far from the centre (make sure it still registers as part of the original village also give it a works station and a villager)
3. trigger a raid whilst in the furthest house
4. then let an illager kill the villager you spawned in the furthest house, then the bossbar says "Raid -defeat" even though villagers are still wandering around.

Video

there is an example of it in this video: 

https://www.youtube.com/watch?v=-ZRj4UYr3nk   

at 18:22 it says "defeat" then at 19:42 you see a villager in one of the houses