Like the title says.
If you charge the bow in your off hand, it doesn't have the arm animations in third-person. It works fine in your main hand.
The screenshots show the difference. The picture with the bow pointed at the ground is when it is in the off 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-88356. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.