In the latest update, clearing/obtaining the Night Vision effect by either drinking milk/potions or doing so with commands can bring some results:

Normal Result:

Night Vision is fully cleared or obtained.

Bugged Results:

Obtaining: The Sky and Entity's are brightened but Blocks are not affected. 

Clearing: The Sky and Entity's are darkened but Blocks remain brightened.

Known Fix:

The only way I've been able to personally fix this bug is by changing my brightness.

Notes:

I tried replicating this bug on Mobile but I couldn't get it to work, so I don't know if this bug only affects Windows Platforms or if this is a problem on my end.

Also, when replicating, it may take multiple attempts for these effects to be seen.

Video Example (MediaFire Download):

https://www.mediafire.com/file/tmxxid7g3lngzw2/Video_Example.mp4/file

Edit:

After doing further testing, I've noticed that this now only happens if 'Improved Input Response' is turned On in 'Video Settings'. This bug may also be related to MCPE-175727