Steps to reproduce:
1. Create a world ^{(or you can use an already created one)}
2. Craft a shield ^{(or use this command when cheats are enabled : /give @p minecraft:shield 1 0)}
3. Get into F5 mode ^{(tap it once)}
4. Hold the right click ^{(so you are blocking)}
5. Watch yourself holding the shield uncorrectly

What i thought that will happen was:
I thought that the I would hold the shield right

What has happened was:
Player (me) holded it wrong