I don't think the algorithm has changed on the device at all.
It's worth noting that since the sensor is inside the watch body, potentially other sources of heat within the watch (the CPU, backlight, battery charging) could affect readings...
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I don't think the algorithm has changed on the device at all.
It's worth noting that since the sensor is inside the watch body, potentially other sources of heat within the watch (the CPU, backlight, battery charging) could affect readings...