After the 1.18 cloud height change, probably to match greater world heights, the cloud layer leaves a gap in the sky after the horizon which makes it looks unnatural.

Possible solutions:

1. revert the cloud height change back to 128?
   1. Maybe hide clouds nearby the player head? (this would make 128 height clouds playable in mountain builds, possibly computationally expensive?)
2. increase cloud view distance and scale to fill the world? (probably the best and natural option, somewhat expensive, I couldn't figure it out how to do this modding the game)
3. increase horizon line a bit?

I've attached some screenshots:

1. current not modded Minecraft clouds
2. modded Minecraft cloud height back to y=128 in 1.19