Need input from DIYers - reducing vibration in DIY phone mount

I built a phone mount at home that works well, except for the excessive vibrations during the shot cycle. i made it from PVC and rubber couplers, hose clamped to the eye piece of my scope. It works incredibly well during regular capture, but gets blurry during the shot. i want to reduce vibration during the shot.

I added a third hose clamp to add reinforcement in the middle of the rubber coupler and that helped, but i think the issue now is the way the phone juts away perpendicular from the scope. Its going to wobble during recoil, and im not sure how i could add some structure to this thing and eliminate the vibrations.

here is my setup: https://youtu.be/9pdbPbRNDt4