This is how the biomes look like with biome blend settings set to 5x5 (default):

Reducing it to 3x3 gives this effect instead (the variation is there, but the color differences get a bit too stark in a lot of places):

Disabling biome blend isn't really an oprion, given the results:

I'm pretty sure 99% of users won't touch the biome blend settings, making the installation of this mod basically useless.
A solution could be to have the effect scale with the biome blend settings?

Do me a favour and take a screenshot of the a super flat world with the default settings

A solution could be to have the effect scale with the biome blend settings?

That is actually not something I had thought about, it could definitely be done to hopefully smooth out the disabled blend

Uhm, in superflat worlds the effect is actually noticeable, for some reason
With 5x5 blending:

With 3x3 blending:

With no blending:

For comparison, this is a 5x5 in a normal world - I feel like it mostly makes everything quite a bit darker, while making the tall grass even more dark in some patches. If you end up making a config file, being able to tweak the min/max brightness values would be appreciated

I propose to make a mod configuration where you can select the Biome noise level from 0 to 16

I think this mod should disable itself if biome blend is turned off.