For left hand mains, there is an animation bug.
When I placed beetroot seeds, I places them with my right arm, while they were in my left hand
1. Options>Skin customization> Main hand: SET TO LEFT
2. Place something while in F5 mode (3rd person mode)
3. See the magic, your right hand places something that is in your left hand.
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-82965. You can find or add further information on that report.
If you haven't, please search before reporting any bugs, as it's likely that one exists already.