When looking at an armour stand that has an enchanted item in its hand, the enchant glint of that item can disappear when looking at it from a certain angle.

To reproduce

1. Create a void world
2. Build a platform

3. /summon minecraft:armor_stand ~ ~ ~ {ShowArms: 1b, HandItems: [{id: "minecraft:diamond_sword", Count: 1b, tag: {Damage: 0, Enchantments: [{lvl: 1s, id: "minecraft:unbreaking"}]}}, {}]}
   

4. Look at the armor stand from certain angles