All the ocean biomes (except the normal frozen ocean) share the same internal "temperature" value (0.5) which determines the coloring of the grass, and because of that the grass color in these biomes is a gray-ish green color, which works well with the regular ocean biomes but clashes with the water colors and "real" temperature of the other ocean biomes, it looks too cold in warm and lukewarm oceans and too warm in cold and deep frozen oceans. While this might seem like a minor issue as these biomes only generate in the ocean, it is still noticeable when these biomes generate on small islands or next to the shore in areas without beaches, and it often clashes with the neighboring biomes and the water colors.

That dull green grass color looks really unfitting in warm oceans, and it's even weirder that the 0.5 temperature value in that biome is the same as the coldest ocean variants, while the neighboring desert biome has a 2.0 temperature value.

The same can be said about the lukewarm ocean, it's weird seeing that dull temperate green color next to the lush and warm jungles.

Actually, that grass color fits rather well with the cold ocean, but having a temperature change in this biome to make it fit well with the taiga would still work.

And lastly, while the regular frozen ocean (in the left side of the picture) has a fitting grass color and temperature value (0.0), it's deep variant still has the same temperature as the warmer oceans, which is unfitting, inconsistent and also doesn't allow for snowfall to happen in this biome, which ironically makes the deep frozen ocean not frozen, but instead full of icebergs and a purplish water to make it look frozen.