I'm trying to simulate CPU throttling using the Chrome DevTools Protocol, by running the following command in the Protocol monitor tab of Chrome DevTools' Drawer:
{"command":"Emulation.setCPUThrottlingRate","parameters":{"rate": 20}}
This yields the following error with version 122 of Google Chrome (whether on macOS or Windows):
{
"code": -32601,
"message": "'Emulation.setCPUThrottlingRate' wasn't found"
}