[MC-233855] When there are villagers in a mansion, there is a chance for a raid to start, if you have Bad Omen.

I spawned villagers in a woodland mansion, got the Bad Omen effect, and a raid started.

Locate a mansion
Use the /effect command to get Bad Omen
Spawn villagers and there is a chance for a raid to start, but raids are only for villages, not woodland mansions.

Attachments

The player can form a village under certain conditions

This room specifically has a cauldron in it, which the villager recognizes as a work station, which counts as a village. Therefore the raid starts.