Hi silbano,
At the moment, the widgets of the Gk theme does not compatible with the Wordpress widgets block, you can add the following code snippet to your functions.php file or by using a code snippets plugin.
function example_theme_support() {
remove_theme_support( 'widgets-block-editor' );
}
add_action( 'after_setup_theme', 'example_theme_support' );
Or the following code:
// Disables the block editor from managing widgets in the Gutenberg plugin.
add_filter( 'gutenberg_use_widgets_block_editor', '__return_false', 100 );
// Disables the block editor from managing widgets. renamed from wp_use_widgets_block_editor
add_filter( 'use_widgets_block_editor', '__return_false' );
