High Server CPU Usage

Hello I understand this question gets asked several times but I'm struggling to find any concrete understanding of causes, all I can find are articles which discuss tweaking to certain server settings but nothing specific, just generalised information. Every so often my process manager in my two servers overloads CPU usage with lots of simultaneous processes running taking up the CPU. They appear as below: /opt/cpanel/ea-php72/root/usr/bin/php-cgi php-fpm: pool insertdomainname_uk Each of these take up between 10-25% CPU usage and then after a while, between 20 mins to an hour the usage dies down. Could someone help me understand why they all run at the same time to generate such high CPU usage? (also what do they mean? They are not related to server traffic across my domains as I've checked this) I've been reading this article found in another support thread -