Night vision potion effect under bedrock level will give full darkness

Description: Drinking or using night vision potion will give full darkness under bedrock level.
What I expected to happen: Night vision potion will allow us to see the void at night too.
Note: It darker then it was regularly.
The pictures: One of the pictures shows without the potion and the darker is with the potion. We can barely see the bedrock without the potion.