Should I trust my Instant Pot or my ThermPro digital thermometer for temperature?
Your digital thermometer may come with a calibrate function where you place it in either ice cold or boiling water and adjust accordingly. Once you have done this, compare the temperature with your IP and this should show you which is the most out (if recalibrating has been required).

https://www.foodrepublic.com/2011/04/04/how-to-calibrate-your-food-thermometer