Web server CPU Utilization slowly increasing with LAMP stack?

I made a ton of changes to my website this year and noticed that my CPU Utilization has been gradually increasing for a couple of months (it slowly went from around 0% to 60% in about 2 months). After restarting my server a couple weeks ago, it went back down to 0% and now it's slowly climbing again.

All of my other stats (such as RAM and Throughput) are basically flat and only CPU usage is climbing. There are no spikes - just a gradual climb. RAM is staying at around 8%.

I implemented HTTP2/push and lazy loading images a few months ago and my suspicion is that 1 of those implementations might be causing this but I'm not 100% sure.

Does anyone know of any common reasons for why this would happen? Could it be something in my PHP code? Is there a way that I can diagnose the issue?

Edit: One thing that I'm going to try is disable HTTP2/push, test, and then do the same for lazy loading images. However, I still don't know if these would cause such a strange problem.

Edit 2: I think this issue might be the same as this: https://stackoverflow.com/questions/64345022/google-osconfigs-cpu-usage-of-vm-on-google-cloud-platform-increases-steadily

Edit 3: I may have found some useful information here (perhaps it's a bug?) - https://github.com/GoogleCloudPlatform/osconfig/issues/228

There was a bug in google-osconfig-agent which now appears to have been fixed. Try sudo apt-get update && sudo apt-get upgrade google-osconfig-agent.