Apparently, Prism Launcher chose to adhere to the idiotic principle of the hidden "trashbin", .Trash-$(uid), invented by Ubuntu. Even though it's based on QT. This can't be disabled. It accumulated 139 GB of literal Trash, fully replaceable, over time. Just ... why? There's even an open issue about this, for over a year, referenced multiple times. I guess I have another point on my agenda.
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
Your desktop environment should have settings for when to clear the trash. You can also use autotrash to clear it automatically.
The Problem is: I don't have a DE, and therefore didn't realize programs would still try to use trashbins.