.
I posted this request to GOOGLE
whether to use sample standard deviation or population standard deviation
Below is what GOOGLE answered me
The population standard deviation is relevant where the numbers that you have in hand
are the entire population, and the sample standard deviation is relevant
where the numbers are a sample of a much larger population.
The source is THIS
https://stats.stackexchange.com/questions/485326/confused-when-to-use-population-vs-sample-standard-deviation-in-engineering-test#:~:text=The%20population%20standard%20deviation%20is,of%20a%20much%20larger%20population.
Probably, it is not 100% rectified answer, which you would want to get,
but it is what is really possible to get.