Thank you for the suggestions. The only plasmoid/widgets beyond stock stuff are system monitor stuff. The issue was there before I added those, though.
Interestingly, I didn’t notice that I haven’t reinstalled kdeconnect since I redid my system last year. Woops. Ah well, now I’m definitely gonna wait to reinstall that…
I was not familiar with hotspot and this has the (extra)gears finally unstuck. The included bug tracker links also provided a few ideas on things to try to help diagnose it, so I’ll try a few more things and report back in detail to hopefully assist others that have run into a similar issue.
I did miss an obvious diagnostic step of moving the config folder temporarily to log into a ‘clean’ environment… I’ll also try that and report back.
EDIT: I moved my .config folder and logged into a clean session. problem gone. So clearly it’s an issue with a file in the .config folder. Another note, I thought going into “display settings” was causing the CPU to go back down, but it’s right clicking on the desktop that’s stopping the CPU usage from spiking, I don’t actually have to go into the display settings. Once the right-click menu appears, CPU goes back down… So… Investigation continues.
I deleted plasmashellrc, didn’t fix it. Investigation continues. Will update as I find moar.
2nd EDIT: config folder deleting was a red herring… i guess i didnt test long enough, because i did it again and it’s back to spiking. Well, there goes that easy fix I guess.