If I time the video with the speed, the g-force is completely off

Here's is another lap I haven't overlaid yet

Here is a screenshot

When I tap the minimum speed in the corner after the straight, it says time: 00:11:64, but on the picture shown with the overlay on, it says 00:15:30

I'm using using GPS from my OnePlus phone. But I'm not sure my calibration is done right. I've mounted the phone I the bottom right corner of the windshield of my Lotus Elise, and is mounted horizontally. I haven't done any calibration, I just used the preset. Here is an example of how the speed is ...

When I overlay my video, everything seems right, but the speed is way ahead. The g-force seems to be right, and the point where
the laptime is collected also seems right, but the speed seems to be a second or so ahead.