In particular, you’ll want to think twice before moving your Steam directory. Github user Keyvin was doing just that by moving his directory from a default location, after which he tried to create a shortcut to the original location. To his surprise, the Steam application then recursively deleted everything in his directory tree—including backups stored on an external hard drive.
Another user reported that his entire Home directory was deleted while debugging Steam. Looks like the problem is a script bug in which an incorrect empty setting gets passed into an rm -rf command that erases files in a given directory, plus all the subdirectories in the home directory (and all their subdirectories, and so on, and so on).
This doesn’t wipe out literally everything—your operating system should still be safe—but it can basically take out all your documents, pictures, saved games, other media and anything else you’ve personally stored.
So if you’re playing Rust or the Talos Principle this weekend and restoring files from cloud backups isn’t how you want to spend your Saturday night, just make sure to avoid symlinking Steam’s .local folders or debugging until a patch is in place. (Looks like one is in the works already.)
Photo by alx_chief