Villages and pillager outposts don't generate in sunflower plains, despite being a plains biome

The bug

Sunflower plains are unable to generate villages or pillager outposts.

How to reproduce

Use the single biome world type and set the biome to sunflower plains, then use the /locate command to find a village or pillager outpost. Neither structure will exist in this world.

Expected Result

Villages and pillager outpost would generate