Process not fully closing on Linux

When I click the "quit" button in game, it closes the window but doesn't fully kill the process. Steam continues to tell me it is running, and it even uses about half a gigabyte of memory despite not being open. Clicking the "quit" button frees up a bit of memory and closes the window, but doesn't seem to actually fix anything other than that.

Process when DST is open:

Process after "closing" DST:

I'm able to force close it using Steam, but it's still inconvenient. Yesterday I forgot to force close it, so I got about 30 hours of play time, which was interesting.

I've had this on every distribution and computer I've used, so it seems like this is a universal Linux bug.