Pure dark areas will have a green-ish yellow hue to them instead of the normal lighting for a bright area when you have the night vision effect. The bottom picture is an example of this next to an area with the normal light levels (due to the lava).
Version:
Hardcore Darkness - 1.12.2-2.0
Forge 14.23.5.2838

I'm relatively sure this is intentional, but I'd like a config option to remove it if possible

@Aetheo Im sorry, no. There is no way that this is intentional. This must be a byproduct with how the gamma or whatever is doing the lighting change

I mean it’s a bit bad for the eyes. But on the other hand it made it look like night vision gave you night vision goggles and not just daylight. So if the bug is getting fixed I would love to see an option that makes night vision get like a green night vision like overlay XD. and instead of giving normal light when looking at torches with night vision you would get the bright green flashes like the lanterns in the picture etc. would fit super good into the hardcore darkness and makes it less likely for people to just ignore the darkness after getting perm night vision items
https://images-eu.ssl-images-amazon.com/images/I/51057J%2BJIzL.jpg

The fact that it looks like the night vision goggles effect is what makes me think it was intentional.

Can this be fixed, please?

Ye I have the same problem i thing the darkness should check for if night vision is enabled or not.

That which is not broken cannot be fixed.