Having the same issue.
After executing the start command inside the container without piping the output to /dev/null (should probably log that output instead....)
The result is this:
6/20/2022 20:20:09: Get create world [worldname]
06/20/2022 20:20:09: failed to load [worldname]
06/20/2022 20:20:09: creating
06/20/2022 20:20:09: Failed to find APPID
06/20/2022 20:20:09: Using steam APPID:0
06/20/2022 20:20:09: Invalid APPID
06/20/2022 20:20:09: Steam is not initialized
06/20/2022 20:20:09: Missing audio clip in music respawn
06/20/2022 20:20:09: Fetching PlatformPrefs 'GuiScale' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'DOF' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'Bloom' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'SSAO' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'SunShafts' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'AntiAliasing' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'ChromaticAberration' before loading defaults
06/20/2022 20:20:09: Fetching PlatformPrefs 'MotionBlur' before loading defaults
06/20/2022 20:20:09: Builder started
NullReferenceException: Object reference not set to an instance of an object
at HeightmapBuilder.Build (HeightmapBuilder+HMBuildData data) [0x0005e] in <6c9b62da23264afb93493ccc5d935b30>:0
at HeightmapBuilder.BuildThread () [0x00067] in <6c9b62da23264afb93493ccc5d935b30>:0
at System.Threading.ThreadHelper.ThreadStart_Context (System.Object state) [0x00014] in <3bd2ef0569bb447ab148a85644c552d7>:0
at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00071] in <3bd2ef0569bb447ab148a85644c552d7>:0
at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <3bd2ef0569bb447ab148a85644c552d7>:0
at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state) [0x0002b] in <3bd2ef0569bb447ab148a85644c552d7>:0
at System.Threading.ThreadHelper.ThreadStart () [0x00008] in <3bd2ef0569bb447ab148a85644c552d7>:0
UnityEngine.DebugLogHandler:Internal_LogException(Exception, Object)
UnityEngine.DebugLogHandler:LogException(Exception, Object)
UnityEngine.Logger:LogException(Exception, Object)
UnityEngine.Debug:LogException(Exception)
UnityEngine.<>c:<RegisterUECatcher>b__0_0(Object, UnhandledExceptionEventArgs)