Due to how the new caves generate, all oceans generate with only stone floors with occasional bits of granite, diorite, andesite, dirt, and gravel. This means that features that depend on these surfaces, like corals, no longer generate. In one world I found a single coral in an entire area within a warm ocean, with occasional sea pickle patches. One way that it could be solved is if in ocean biomes, caves will only generate below a certain height in the world.