A log is to protocoll what is going on. I would not speak of spamming.
Have you tried safe mode to find out what plugin my be the cause?
BTW: You may check the PSU of the Pi:
2023-08-17 08:56:32,037 - octoprint.plugins.pi_support - WARNING - This Raspberry Pi is reporting problems that might lead to bad performance or errors caused by overheating or insufficient power.
!!! UNDERVOLTAGE REPORTED !!! Make sure that the power supply and power cable are capable of supplying enough voltage and current to your Pi.
I think you just have the log setting for the Tornado log file set to info. I keep mine set to critical when I am not having any issues with requests. You will likely have other things listed different than I do but if you look in the logging section of settings, you should see tornado listed there. I think Critical is default as well.
If there are lots of API requests like this being sent, it's usually from a 3rd party client like a smartphone app, or touchscreen app that doesn't work with the websocket and just polls the API continuously.
Re undervoltage: This happens only on system power up as there is no other messages in the log files. My system has some custom electronic components and I've always put the power warning down to an initial surge for power on startup.