This is most likely a caused by really high frequency vibrations. We have developed a Smartphone Damper Mount that fixes this, and with it you can get super smooth dynamic footage with your phone.
When using gimbals, dollies, cable cams, dash cams or any other electronic product to get dynamic shots, there will always be some high frequent vibrations in your setup. These vibration are not noticeable in most cameras, but might cause a problem when it comes to smartphones. This is because a lot of the new smartphones on the market comes with an Optical Image Stabilization (OIS) feature. This stabilization works great to stabilize larger movements, like when you’re holding the phone in your hand. In combination with high frequency vibrations however, the OIS often overcompensates for the movement and amplifies the vibrations resulting in a jello or warping effect.