Since 19w42a, dropped items are no longer affected. Armor stand effects are essentially unchanged since the last snapshot. Also this bug still applies to items held by endermen.
Item models render their shadows differently, depending on at which angle the player is looking at them. When looking at a block on the head of an armor_stand, the shading changes drastically depending on how the camera is viewing it.
Summon an armor stand with a stone head item and circle the cursor around it while staying still. Note the brightness changes.
Note that this is a stone block on the head of an armor_stand, so it is being rendered as an entity not a block in the world.