Might be related/relevant that I run Awesome WM, which is not a desktop manager, just a window manager.
I am getting a similar issue on Ubuntu. It is different in that the client doesn't say the game is "running," the game just fails to start after the "Preparing to launch Artifact..." window opens (and then immediately closes).
After installing Artifact, trying to run it from the Steam client does not start the game. A "Preparing to launch Artifact..." window comes up but then closes quickly. I've verified the local files.
EDIT: This seems to be a problem with a recent Nvidia driver update. After rebooting, both Dota 2 and Artifact give the same "Failed to initialise vulkan" error. Dota 2 used to work fine with vulkan.
EDIT 2: Definitely a problem with the driver. I downgraded to nvidia-410 from nvidia-415 which has fixed my problem.
Hello @stevenroose, are you still experiencing this issue on an up to date system?
Closing pending feedback.
Your system information
Steam client version (build number or date): (can't copy this)

Arch package
steam-1.0.0.56-1System Information: https://gist.github.com/stevenroose/1fb78734c34f3a5cb8ee6296b0e38270#file-system-information-txt
Distribution: Arch Linux
Opted into Steam client beta?: No
Have you checked for system updates?: Yes
Please describe your issue in as much detail as possible:
(Could be related to https://github.com/ValveSoftware/steam-for-linux/issues/5925.)
When trying to launch Artifact, it shows "Running" but no window shows up. Trying again gives an error saying the game is already running.
stderr and stdout output while doing this: https://gist.github.com/stevenroose/1fb78734c34f3a5cb8ee6296b0e38270#file-steam-artifact-log
These processes show up:
Steps for reproducing this issue: