We described it properly when opening ticket, I reformulate :

Usually, 1 nginx worker process consumes 1.16-2% of RAM maximum on this server, and it remain stable.
For some days after nginx upgrades, every overnight, during daily stat generation process of cpanel which happens on overnight like set, there is many nginx reloads due to stat generation (= normal), but this is now causing an ever increasing memory use of RAM by nginx worker process, usually it stays around 1-2% RAM, we now see it cumulating after stat generation process increasing itself at begin with 1-2% RAM each time, which will lead after some weaks to a saturated server in term of RAM if nginx is not started. When we saw the issue first time, Nginx was consuming 12% of server RAM considering we have 128 GB RAM on this shared hosting server.

After recent nginx upgrade :
The increase is around 0.20% daily, instead of 1-2% RAM