This question already has an answer here:
By my count, I should have 40-50gb free. But starting a few weeks ago, I'd wake up having created no new files, and 5gb would be gone, or 10gb.
Today, it told me that no storage was left. I freed up 5gb by deleting some apps I no longer used... and it has slowly eaten that as I watch the finder window's footer. Down to 546mb at the moment. And there's nothing else left to get rid of.
What the hell is going on? I have a Terminal.app open. I have a Firefox window open (that I'm typing into right now). And a few Sublime tabs.
If I reboot, I'll get maybe 11-12gb of this back... and it will slowly gobble that up over a period of at most a few hours. I don't know what's going.
I don't think this is malware, no files are messed up anywhere, no ransomware horseshit. Where do I start checking? Down to 373mb now.
It has done this in the past, of course, but an hour later whatever it was using that storage for would be freed, and I'd have no incidents for weeks/months afterward. This is the first time that it didn't self-correct.