GPS Data inconsistency with the Z1

Are you using the webAPI to save the metadata into the still image?

https://github.com/ricohapi/theta-api-specs/blob/main/theta-web-api-v2.1/options/gps_info.md

If so, post the snippet that you are using to store the information.

example:

{
    "gpsInfo": {
        "lat": 23.532,
        "lng": 23.532,
        "_altitude": 999.00,
        "_dateTimeZone": "2014:05:18 01:04:29+08:00",
        "_datum": "WGS84"
    }
}

Is the difference in the GPS coordinate due to the time taken to stitch and save the image inside the camera?

There is a discussion on the creation time and modification time.

EXIF Tag Documentation - #5 by craig

You may be able to get more information on the difference by opening an issue on GitHub on the API specification section.

https://github.com/ricohapi/theta-api-specs/tree/main/theta-web-api-v2.1