If you do not set the same incline on your treadmill that the workout suggests, your power information will be wrong. The Stryd pod does not measure incline independently from the app. The app corrects the power data that is recorded based on the inline displayed in the workout.
Not setting the treadmill incline to the correct number can cause your Critical Power to be incorrect. This will negatively impact your future workouts and races.
If you have any questions please contact Stryd support.