What you are seeing is a change made in the latest app release. It was intentional as there were many complaints about the video being stretched. What you are seeing now is actually not squashed but is the natural ratio of the video.
In the previous version, the view was stretched vertically to fill the screen, but everything was stretched. This was great if you were trying to lose some weight and stood in front of the camera. But it actually was distorted and has now returned to true aspect ratio. I think perhaps you were used to it being stretched and that’s why it now looks squashed to you.