Unfortunately as of right now (April 2025) there are issue with Electron PowerMonitor on Linux systems, specifically when you are using Wayland under the hood (which is the default). I won't pretend I understand everything about this issue, but it does seem that it might be an upstream issue (meaning there is not much Electron can do about it directly), meaning a fix might take some time to appear (source: https://github.com/electron/electron/issues/27912)
Personally I ended up building my own native code to do this in a cross platform way, and ended up forking, updating and re-releasing a project that was tackling the same issue 8 years ago. I plan to keep using it and supporting it for as long as this remains an issue remains, hope someone else finds it helpful.