[Bug of flatpaked Steam or Sandbox problem] Cannot start steam, when it's running

I think that title describes problem.

I created this little script:
#!/bin/bash
echo $@
flatpak run com.valvesoftware.Steam “$@”

When running it, ever Steam is running, dialog asking for migrate data popups. But that's not real problem. The game won't start (if flatpaked Steam is running). I thnik Steam quits, because there's file look and it cannot talk to running Steam process. I'm not sure it's true, so that's an sandbox/flatpak problem or that's flatpaked Steam version problem. I looked at script on https://github.com/flathub/com.valvesoftware.Steam/blob/master/steam_wrapper/steam_wrapper.py

I didn't read it full, but this line seems to good work:
os.execve(steam_binary, [steam_binary] + sys.argv[1:], os.environ)