Stryd has a barometer to detect wind and elevation. The barometer requires a hole in the bottom of the device. Since it is open to the elements, water can block or enter the hole. This will temporarily affect the power reading. Normally, it will be a spike of a few seconds but it may persist. Once water disappeared from the hole or evaporated, your device will be back to normal.
Stryd is water-resistant and will not be damaged by running in rain (although we advise against running through deep standing water).
If you need additional assistance, contact firstname.lastname@example.org.