Minecraft beds only requiring 1 block to place?

Since when have beds only required 1 block to place underneath? I can’t find ANY documentation of this change anywhere. When I place a bed on 1 grass block in my vanilla super flat world, with no data packs, it places the end piece and the head piece away from me (like a regular bed) except the head piece is floating since there’s no block below it. All I’m wondering is when this happened.