My screenshot shows Gnome 3.26.2 alt+tab menu on Arch Linux.
Created attachment 110359 [details] screenshot
Could you look into it a bit? kamoso.png is already installed in hicolor: https://www.archlinux.org/packages/community/x86_64/kamoso/
kamoso icons are available on my file system. But alt+menu and dash (bar on left) show wrong icon. before install the package from Arch repositories, I installed flatpak version, but it did not work, I only got a black screen. It was already uninstalled.
icon of kamoso 18.04.1 is correct on Gnome 3.28.2.