The animation is set to loop in your panel for the Page Scroll. I can see the animation bouncing too in Chrome because of this option is set.
To correct it: Turn off Loop.
If you want an animation to repeat when you scroll out and back in again, you need to set the interaction for when it leaves the page, it will then do the animation when you scroll back in.
Loop is used, so if you have an element rotate 360 for example, loop will keep it going again and again.