Change:
<del> { fetchurl, lib, stdenv, dpkg, makeWrapper, alsa-lib, brotli, cups, curl, dbus, expat, fontconfig, freetype, glib, gst_all_1, harfbuzz, lcms, libcap, libevent, libGL, libGLU, libkrb5, libopus, libpulseaudio, libxkbcommon, libxkbfile, libxml2, libxslt, libwebp, mesa, nspr, nss, openssl, snappy, systemd, wayland, xorg, zlib, zstd, ... }: stdenv.mkDerivation { pname = "viber"; version = "21.8.0.11"; src = fetchurl { # Official link: https://download.cdn.viber.com/cdn/desktop/Linux/viber.deb url = "https://download.cdn.viber.com/cdn/desktop/Linux/viber.deb"; hash = "sha256-9WHiI2WlsgEhCPkrQoAunmF6lSb2n5RgQJ2+sdnSShM="; }; nativeBuildInputs = [ makeWrapper ]; buildInputs = [ dpkg ]; dontUnpack = true; libPath = lib.makeLibraryPath [ alsa-lib brotli cups curl dbus expat fontconfig freetype glib gst_all_1.gst-plugins-base gst_all_1.gstreamer harfbuzz lcms libcap libevent libGLU libGL libkrb5 libopus libpulseaudio libxkbcommon libxkbfile libxml2 libxslt libwebp mesa nspr nss openssl snappy stdenv.cc.cc systemd wayland zlib zstd xorg.libICE xorg.libSM xorg.libX11 xorg.libxcb xorg.libXcomposite xorg.libXcursor xorg.libXdamage xorg.libXext xorg.libXfixes xorg.libXi xorg.libXrandr xorg.libXrender xorg.libXScrnSaver xorg.libXtst xorg.xcbutilimage xorg.xcbutilkeysyms xorg.xcbutilrenderutil xorg.xcbutilwm ]; installPhase = '' dpkg-deb -x $src $out mkdir -p $out/bin # Soothe nix-build "suspicions" chmod -R g-w $out for file in $(find $out -type f ( -perm /0111 -o -name *.so* ) ); do patchelf --set-interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" "$file" || true patchelf --set-rpath $libPath:$out/opt/viber/lib $file || true done # qt.conf is not working, so override everything using environment variables wrapProgram $out/opt/viber/Viber  --set QT_QPA_PLATFORM "xcb"  --set QT_PLUGIN_PATH "$out/opt/viber/plugins"  --set QT_XKB_CONFIG_ROOT "${xorg.xkeyboardconfig}/share/X11/xkb"  --set QTCOMPOSE "${xorg.libX11.out}/share/X11/locale"  --set QML2_IMPORT_PATH "$out/opt/viber/qml" ln -s $out/opt/viber/Viber $out/bin/viber mv $out/usr/share $out/share rm -rf $out/usr # Fix the desktop link substituteInPlace $out/share/applications/viber.desktop  --replace /opt/viber/Viber $out/opt/viber/Viber  --replace /usr/share/ $out/share/ ''; dontStrip = true; dontPatchELF = true; meta = { homepage = "https://www.viber.com"; description = "Instant messaging and Voice over IP (VoIP) app"; sourceProvenance = with lib.sourceTypes; [ binaryNativeCode ]; license = lib.licenses.unfree; platforms = [ "x86_64-linux" ]; maintainers = with lib.maintainers; [ jagajaga ]; }; } </del>

Discussion:
Steps to reproduce the behavior: the last commit removed the use of webarchive <!-- Please @ people who are in the list of the offending package or module. If in doubt, check for whoever last touched something. -- Please run and paste the result. Add a :+1: [reaction] to [issues you find important]. [reaction]: [issues you find important]:
Hello, I'm not the maintainer. I think you meant to ping :+1:
I think there is one issue with latest viber update - it use url downloaded directly from viber instead of former practice using which lead to the hash mismatch issues. I tried following overlay to fix them The latest file from viber for linux with the hash have some hard code that result failed to launch with message that on NixOS