Messy detected data from LED green sensor

I have been studying and collecting data detected from LED green sensor using Galaxy Watch Active 2 which should be in range 0 to 1081216 as stated in the documentation:
However, the data that I obtained can be below 0 and most of the time can be more than 2000000.
I’m using the code shared on here to collect the data.
The other problem is, when I plot the data, it does not look like the PPG wave that I expected to be.
Is it the sensor problem or collecting PPG from LED green sensor is just not reliable?

The issue does nor occur in my Galaxy watch (SM-R810). I have used the exact same code you mentioned here. I always get the value in the valid rage defined here.

Have you tried the same in any other watch?

Thank you for your response. I haven’t tried in any other watch. However, I found a screenshot of someone who did the same here and his data value is shown 4196826 which is also larger than the valid range.