The Stryd platform automatically calculates your critical power based on the last 3 months worth of your running data. If there is an issue with your auto-CP, you can reset the calculation so that only runs from that point forward are being considered. You will get a new CP number after a few runs and the platform will again collect 3 months' worth of data.
You can currently only reset the critical power calculation with the Stryd app on the phone. Select Settings > Critical Power. Above the watt/kg number, you will see three dots. Select those dots, and you will get the option to reset CP. Below the image from the Android app:
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