Plugin Usage Report for the Network

if ( ! is_multisite() ) {
    return;
}

add_action( 'network_admin_menu', function () {
    add_submenu_page( 'plugins.php', __( 'Plugin usage' ), __( 'Usage' ), 'manage_network_plugins', 'wpide-plugin-usage', function () {
        if ( ! current_user_can( 'manage_network_plugins' ) ) {
            return;
        }

        require_once ABSPATH . 'wp-admin/includes/plugin.php';

        $usage = get_site_transient( 'wpide_plugin_usage' );

        if ( false === $usage ) {
            $usage = array();
            foreach ( get_sites( array( 'number' => 0, 'fields' => 'ids', 'deleted' => 0 ) ) as $blog_id ) {
                foreach ( (array) get_blog_option( $blog_id, 'active_plugins', array() ) as $file ) {
                    $usage[ $file ][] = (int) $blog_id;
                }
            }
            set_site_transient( 'wpide_plugin_usage', $usage, HOUR_IN_SECONDS );
        }

        $network = (array) get_site_option( 'active_sitewide_plugins', array() );

        echo '<div class="wrap"><h1>' . esc_html__( 'Plugin usage' ) . '</h1>';
        echo '<table class="widefat striped"><thead><tr><th>' . esc_html__( 'Plugin' ) . '</th><th>' . esc_html__( 'Sites' ) . '</th><th>' . esc_html__( 'Where' ) . '</th></tr></thead><tbody>';

        foreach ( get_plugins() as $file => $data ) {
            $sites = isset( $usage[ $file ] ) ? $usage[ $file ] : array();

            if ( isset( $network[ $file ] ) ) {
                $where = '<strong>' . esc_html__( 'Network active' ) . '</strong>';
                $count = esc_html__( 'All' );
            } else {
                $count = count( $sites );
                $links = array();
                foreach ( array_slice( $sites, 0, 20 ) as $id ) {
                    $links[] = '<a href="' . esc_url( get_admin_url( $id, 'plugins.php' ) ) . '">#' . (int) $id . '</a>';
                }
                $where = $links ? implode( ' ', $links ) . ( count( $sites ) > 20 ? ' …' : '' ) : '<span style="color:#b32d2e">' . esc_html__( 'Unused' ) . '</span>';
            }

            printf( '<tr><td>%1$s</td><td>%2$s</td><td>%3$s</td></tr>', esc_html( $data['Name'] ), esc_html( (string) $count ), $where ); // phpcs:ignore WordPress.Security.EscapeOutput -- $where is built from escaped parts.
        }

        echo '</tbody></table></div>';
    } );
} );

add_action( 'activated_plugin', function () {
    delete_site_transient( 'wpide_plugin_usage' );
} );
add_action( 'deactivated_plugin', function () {
    delete_site_transient( 'wpide_plugin_usage' );
} );