You are tired. What you are doing is relaxing your bow arm at the same instant you are hitting the trigger. You are doing this without realizing it. But your arm is tired and wants to relax as soon as possible and is doing it at the same time as the trigger is hit.

What makes it worse is, once you start missing you want to see where you hit and then you start trying to watch the arrow or want to see where you hit. YOU ARE NOT FOLLOWING THROUGH.

This happens to lots of people when they start missing.

I think it is a combination of the two, especially when the arrow hits way off the mark.

Try to concentrate on holding the pin on target until you hear the arrow hit. {following through}

It is probably best that you take a beak when shooting so that you do not practice bad habits.