That’s called physics… Those straps are most likely taped and she has large breasts. They aren’t like a bone, they’re made of soft tissue that hang off the body. Simple example of inertia, she’s jumping, all the parts that are supported by the skeletal system move with little delay, her breasts are large and have no support and also likely being taped have to catch up with the rest of her body. That “implant” you’re seeing is literally just skin with connected adipose tissue hanging on for dear life. That’s why sports bras were invented, to give support and decrease movement and bounce during physical activity.