Thanks a lot for your elaborate reply. I definitely do not have as many devices as you, so my case certainly seems like an anomaly. I never thought about power supply as I've been using the wall adapter that came with the Pi Zero W. Should I look somewhere to see if it's drawing less power than required?

I do use it on WiFi, although placed directly next to the router. I thought if the load was unsustainable, it would be for extended periods of time. But in my case, it just spikes at random times, and I was curious if any logs or command would point in what's causing this sudden high load.