Edit3: It's back to 80%, without me opening a terminal. That's so weird, it's been at ~10% for 10-15 minutes now. I didn't open a new app or anything. Didn't start a new process either. I'm just browsing stackexchange on firefox that's pretty much it.
Edit4: Just closed telegram messenger. It went back to 10% for a minute, then back to 80%. Within that minute I didn't use the computer at all, I just watched the process monitor.