Summary:

As far as I've tested, only minecarts with chests have this vulnerability, others such as minecarts with hoppers don't

Steps to reproduce:

1. Place the minecart with the chest in a dark place
2. You'll notice that the farther away you are, the brighter the box looks

Observed Results:

look at the picture

Expected Results:

No matter how far the player is away from the minecart, the chest inside the minecart will always have the same brightness as the minecart