Should I trust my Instant Pot or my ThermPro digital thermometer for temperature? I cook sous vide in my Instant Pot Ultra (which lets you set a precise temperature), but when I check the water temperature with my digital thermometer, it is a few degrees off (I believe the thermometer reads 3-4 degrees higher). This temperature difference can change how done meat gets, so which which one should I trust?  My instinct is to trust the thermometer, since it was made for a single purpose, but is that right? Should I trust the instant pot instead because it's more expensive?  Which would likely have a more accurate thermometer?
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