Currently an icon is being provided by gentoo in ${FILESDIR}, this is not needed as upstream tarball already includes an icon Attached diff modifies ebuild to use it Reproducible: Always
Created attachment 164815 [details] mozilla-firefox-bin.ebuild.diff It also moves "newicon" to the start, before mv "${S}" "${D}"${MOZILLA_FIVE_HOME} , if not, it won't find the icon
Done, thanks for the patch.