Comment 9 for bug 1951210

I just verified that indeed xdg-open (in fact gio that is invoked by xdg-open) is tripped by URLs with parameters.

This would require patching impl_showOfflineHelp() to write the temporary file to some place strictly confined snaps such as firefox can see, e.g. XDG_DOWNLOAD_DIR. Not exactly a clean solution, but better than failing to display the help altogether.