Question - Why do I keep losing storage space despite deleting? (opens in new tab)

OK, so any ideas? I have 23U. It's a little short of storage space. Of the 512gb, I was down under 13gb free, got warnings from the System. So, I deleted some Audio files, made sure they weren't in recycle bin. Got back to about 22gb free. I look up a few days later, down to 17gb. A few days...