All-black shadows in custom blocks

I am here to report a recurring bug that has been happening with addon creators. This bug has existed since version 1.16 to the current one.

The bug is that blocks with custom models, smaller than 1 block of space, have very dark shadows when positioned near a wall of opaque blocks. This only happens with custom blocks, but it does not happen with blocks from the base game.

This darkness is supposed to occur, but in "vanilla" blocks this shadow is more subtle, while in custom blocks, the shadow is absolute black.

This bug has always occurred in ALL versions of the game!

In the video I sent below, I show a block from the base game, next to a custom block, notice the difference in the shadow on the two blocks. I also put the .mcaddon file to test the bug.