The bug

Bonus chests sometimes can generate on top of village houses.

How to reproduce

Seed [superflat, Classic Flat preset]: -1154973073459112131
Coordinates: /execute in minecraft:overworld run tp @s -215.04 12.00 228.77 28.50 37.50

Note: it can take multiple re-creations of the world until the bonus chest spawns on top of the house.