In /proc/pid/limits, where does the hard limit value come from?

I didn't set the hard limit value in /etc/security/limits.d/<xx.conf> and /etc/security/limits.conf.There's only soft limit value 4096 set.Then I go to /proc/, and cat the limits. I saw 31839 is set for hard limit. I don't really know where this value coming from.

I checked the values in some max_xx_namespaces files in /proc/sys/user, and it turns out 31839 is also in these files like max_pid_namespaces.

Is there any relationship between the two setting? or the hard limit 31839 is coming from some kernel related setting?

Thank you!