3080 with nvidia 530 driver.
Steam --reset does not enable it to start.

I will try that tonight when I get home.

Thanks.

If Steam is crashing hard enough or early enough, then the log files that it records by default will not necessarily have the full story. I'd recommend running it from a terminal (xterm or equivalent), and pasting the last few lines before the crash from there.

In particular, if this is #9805, then the assertion message is distinctive:

Assertion 'device' failed at src/libsystemd/sd-device/device-private.c:103, function device_get_tags_generation(). Aborting.

Here is the result of running steam from a terminal:

[s@Sentinel Desktop]$ steam
steam.sh[10214]: Running Steam on manjarolinux 23.0.0 64-bit
steam.sh[10214]: STEAM_RUNTIME is enabled automatically
setup.sh[10288]: Steam runtime environment up-to-date!
steam.sh[10214]: Steam client's requirements are satisfied
[2023-08-01 00:02:30] Startup - updater built Jul 10 2023 23:58:24
[2023-08-01 00:02:30] Startup - Steam Client launched with: '/home/s/.local/share/Steam/ubuntu12_32/steam'
08/01 00:02:30 Init: Installing breakpad exception handler for appid(steam)/version(1689034492)/tid(10354)
Looks like steam didn't shutdown cleanly, scheduling immediate update check
[2023-08-01 00:02:31] Loading cached metrics from disk (/home/s/.local/share/Steam/package/steam_client_metrics.bin)
[2023-08-01 00:02:31] Using the following download hosts for Public, Realm steamglobal
[2023-08-01 00:02:31] 1. https://client-update.akamai.steamstatic.com, /, Realm 'steamglobal', weight was 1000, source = 'update_hosts_cached.vdf'
[2023-08-01 00:02:31] 2. https://cdn.cloudflare.steamstatic.com, /client/, Realm 'steamglobal', weight was 1, source = 'update_hosts_cached.vdf'
[2023-08-01 00:02:31] 3. http://media.steampowered.com, /client/, Realm 'steamglobal', weight was 1, source = 'baked in'
[2023-08-01 00:02:31] Checking for update on startup
[2023-08-01 00:02:31] Checking for available updates...
[2023-08-01 00:02:31] Downloading manifest: https://client-update.akamai.steamstatic.com/steam_client_ubuntu12
[2023-08-01 00:02:31] Manifest download: send request
[2023-08-01 00:02:31] Manifest download: waiting for download to finish
[2023-08-01 00:02:31] Manifest download: finished
[2023-08-01 00:02:31] Download skipped: /steam_client_ubuntu12 version 1689034492, installed version 1689034492, existing pending version 0
[2023-08-01 00:02:31] Nothing to do
[2023-08-01 00:02:31] Verifying installation...
[2023-08-01 00:02:31] Performing checksum verification of executable files
[2023-08-01 00:02:32] Verification complete
Loaded SDL version 3.0.0-1782-g214d5daa3
XRRGetOutputInfo Workaround: initialized with override: 0 real: 0xf30e0db0
XRRGetCrtcInfo Workaround: initialized with override: 0 real: 0xf30df500
/usr/share/themes/Matcha-sea/gtk-2.0/main.rc:1113: error: unexpected identifier 'direction', expected character '}'
/usr/share/themes/Matcha-sea/gtk-2.0/apps.rc:91: error: unexpected identifier 'direction', expected character '}'
GetWin32Stats: display was not open yet, good
GetWin32Stats: display was not open yet, good
steamwebhelper.sh[10367]: Runtime for steamwebhelper: defaulting to /home/s/.local/share/Steam/ubuntu12_64/steam-runtime-heavy
steamwebhelper.sh[10367]: glibc >= 2.34, partially disabling sandbox until CEF supports clone3()
CAppInfoCacheReadFromDiskThread took 45 milliseconds to initialize
src/steamUI/steamuisharedjscontroller.cpp (538) : Failed creating offscreen shared JS context
src/steamUI/steamuisharedjscontroller.cpp (538) : Failed creating offscreen shared JS context
src/steamUI/steamuisharedjscontroller.cpp (538) : Fatal assert; application exiting
src/steamUI/steamuisharedjscontroller.cpp (538) : Fatal assert; application exiting
08/01 00:03:04 Init: Installing breakpad exception handler for appid(steam)/version(1689034492)/tid(10354)
_ExitOnFatalAssert
assert_20230801000304_30.dmp[10497]: Uploading dump (out-of-process)
/tmp/dumps/assert_20230801000304_30.dmp
[s@Sentinel Desktop]$ assert_20230801000304_30.dmp[10497]: Finished uploading minidump (out-of-process): success = yes
assert_20230801000304_30.dmp[10497]: response: CrashID=bp-482a3bda-8ec1-4f11-95a1-1a3df2230731
assert_20230801000304_30.dmp[10497]: file ''/tmp/dumps/assert_20230801000304_30.dmp'', upload yes: ''CrashID=bp-482a3bda-8ec1-4f11-95a1-1a3df2230731''
^C
[s@Sentinel Desktop]$

This looks like a separate issue, and src/steamUI/steamuisharedjscontroller.cpp (538) : Failed creating offscreen shared JS context is probably the distinctive message here.

Any idea how to fix it?

I'm looking at it but there is a lot to read.
do you want me to go sequentially and try everything that anyone said worked for them?

That worked!

I typed pacman -R xdg-desktop-portal-gnome into a terminal to remove it and now Steam starts.