Your system information

• Steam client version (build number or date): 1.0.0.74-1
• Distribution (e.g. Ubuntu): Arch Linux with Sway (wayland WM)
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Steam suddenly does not open. Instead, it shows a popup window with the following content:

Check your DISPLAY environment variable and make sure that you have enabled X.
If you are running remotely, make sure that you have a remote connection which will allow an X connection.
For more information visit https://support.steampowered.com/kb_article.php?ref=4050-WOJB-0608

The referenced link is dead.

Note that I'm running Wayland but this has never been an issue until today. Same issue when running Steam with the SDL_VIDEODRIVER=x11 environment variable.

The following output results from launching from command line:

steam.sh[151139]: Running Steam on arch rolling 64-bit
steam.sh[151139]: STEAM_RUNTIME is enabled automatically  
setup.sh[151213]: Steam runtime environment up-to-date!  
steam.sh[151139]: Steam client's requirements are satisfied
[2022-07-01 18:49:24] Startup - updater built Jun  7 2022 03:18:19
Installing breakpad exception handler for appid(steam)/version(1654574690)
src/steamexe/updateui_xwin.cpp (339) : Could not open connection to X
src/steamexe/updateui_xwin.cpp (339) : Could not open connection to X
Installing breakpad exception handler for appid(steam)/version(1654574690)
assert_20220701184924_4.dmp[151278]: Uploading dump (out-of-process)
/tmp/dumps/assert_20220701184924_4.dmp
src/steamexe/main.cpp (1009) : failed to initialize update status ui, or create initial window
src/steamexe/main.cpp (1009) : failed to initialize update status ui, or create initial window
 alessandro  ~  $  
(zenity:151275): Gtk-WARNING **: 18:49:25.079: Theme parsing error: gtk-contained-dark.css:2871:228: Missing closing bracket for :not()
assert_20220701184924_4.dmp[151278]: Finished uploading minidump (out-of-process): success = yes
assert_20220701184924_4.dmp[151278]: response: CrashID=bp-2e1725bb-5d7a-4c48-8120-c8b2a2220701
assert_20220701184924_4.dmp[151278]: file ''/tmp/dumps/assert_20220701184924_4.dmp'', upload yes: ''CrashID=bp-2e1725bb-5d7a-4c48-8120-c8b2a2220701''

And the .dmp file (renamed to .txt or Github won't take it):
assert_20220701184924_4.dmp.txt

Steps for reproducing this issue:

1. Launch Steam