Apple Watch heart monitor is inaccurate
Apple Watch reports that my heart rate is between 35 to 125. When checked at the hospital it is disproven that it never goes belo w 58 to 130
Apple Watch Series 10, watchOS 11
An Apple Watch is not a medical device of course, so it could be that readings on the watch are not that accurate as a reading on a medical device
B it you can restart the watch to see if the issues persist