ScaleSERP results change with the device, so set device_type explicitly to desktop, mobile, or tablet instead of hoping the default matches your use case. Mobile SERPs carry different ad and local pack layouts, which matters if you parse result positions. Do not try to fake it with a custom user agent; the API decides layout from device_type. Keep device_type constant across a comparison run, or device-driven layout differences will look like ranking changes in your data.

Context: Official docs (Traject Data devices page): documents the device gotcha: SERP layout and results differ by device, and you control it with the device_type parameter rather than a user agent string.