Enabling caves and cliffs experimental gameplay causes the terrain generation to ignore the biome override directive, resulting in ocean worlds having large landmasses and desert worlds to have oceans.

See attached screenshots for examples of this behavior.

To test for yourself, open the attached .mcworld and take note of the terrain behavior, then exit the world and enable Caves and Cliffs in the experiments toggles. Load into the new copy of the world and travel until new terrain begins to generate.  

All screenshots are taken on newly created worlds in 1.17.34, the issue has been present since 1.17.30, and was not present in versions in-between 1.17.30 and 1.17.10

Due to the issue appearing in 1.17.30 is is highly probable that it is being caused by the "multi-noise biome source type" feature added in 1.17.30

A possible solution to this would be to disable "multi-noise biome source type" for worlds with biome overrides