How can I identify the cause of site outages?

I am trying to troubleshoot a WP site that is experiencing periodic outages. The outages run 1 to 5 minutes in duration and occur at all hours. The site is hosted at GoDaddy and the shared server has 2 GB of memory allocated to it. There are some PHP warning messages in the WP debug log but no PHP fatal messages. The version of WP is 5.4.4 and PHP is 7.2.

I have cloned the site on another server with 2 CPUs and 4 GB of memory and updated all plugins and WP as well as PHP to 7.4.

Prior to GoDaddy upgrading memory from 512MB the server experienced a lot of PmemF errors but they seem to have gone away. Now it’s just the periodic outages.

I would be grateful for any troubleshooting tips as I do not know where to look anymore.