The bug
When going underwater in different biomes, you see a different background color. This color corresponds to the color of the water when seen from above. But when you turn biome blend on (in the example pictures to 15x15), then the color of the water as seen from above changes, but the color seen from underwater does not adjust.
Linked issues
is duplicated by 1
relates to 3
Attachments
Comments 7

Please, update this. Not fixed and confirmed for 1.15 all the way to 20w07a
Confirmed for 20w12a, can I request ownership?

I have the impression that this bug has been fixed in 1.16 Pre-Release 6. Can anyone confirm that?
Still not fixed. The fog color still doesn't vary depending on biome blend, as only one biome could affect fog color at a time.
Confirmed in 1.16.2 Pre-release 3.

This is a feature request.
Does this affect 1.13-pre4? If so, update your issue accordingly.