XZS  filed a request to merge gnome-shell-extension-buttons-to-panel  into gnome-shell-extension-window-buttons-git :
buttons-to-panel is no longer under active development and not compatible with the current gnome-shell version. window-buttons provides the same functionality and is up to date, so users are advised to switch to it. Merging the packages would reflect this.
 https://aur4.archlinux.org/account/XZS/  https://aur4.archlinux.org/pkgbase/gnome-shell-extension-buttons-to-panel/  https://aur4.archlinux.org/pkgbase/gnome-shell-extension-window-buttons-git/