Lush Caves not spawning

From the snapshot's changelog

The Lush Caves underground biome now exists for use in single-biome worlds. It does not yet generate in other world types.

https://www.minecraft.net/en-us/article/minecraft-snapshot-21w10a

Oh, sorry didn't notice!

Should be reopened because they now naturally generate on Bedrock Edition.

Only under "Experimental Gameplay". It will probably be under experimental until Bedrock 1.18.0.

I think lush caves should generate naturally, but only with Caves&Cliffs datapack enabled (until 1.18).