I'd say it is definitely a frame scan effect of the camera.
There is no way the arrow leave the string that early...there are some stupid myths about such stuff.
The maximum acceleration will be early on, but the string and arrow will still be accelerating until the string hits full travel.
The
rate of acceleration may be slowing but it is still acceleration.
The way to look at it is... at any point the limbs are returning at speed V, what forces are acting on them? There is still force acting to make them return even more, so thay are still gaing speed (maybe not as quickly as at the loose, but they are still gaining speed.
The only thing slowing them is the inertia of the arrow, string and a tiny bit of wind resistance.
For the arrow to leave the string the limbs would have to be actively slowing down which would require a force in the opposite direction...that would mean the limbs would need to be trying to come back towards the archer
... reductio ad absurdum.
I've seen some V weird scan effects from digital cameras, so chill out man.
del
