When selecting the biome in Single Biome world gen, one would expect to see that biomes which are ocean generate as an ocean with nearly the entire surface below y 63. However, the ocean biomes generate much the same as any other biomes, leading to large amounts of hills and sometimes mountains and very small oceans.

I know exactly why this is happening, but since very few people ever think about the other world options this seems to have been ignored. I would suggest that Single Biome generation (as well as Island and Cave generation when they are reimplemented) be reverted to pre-1.18 terrain noise so people can play in ocean-only worlds and have an actual challenge finding resources instead of just spawning on a hill and finding everything easily.