Currently, GB query loop block can only select 1 post type for the query loop, if you want to add multiple post types in one query loop block, you can use the below method.
1. Add a CSS class to the Query loop block
Add a CSS class to the Grid block of the Query loop block.

2. Use generateblocks_query_loop_args
to merge queries
The below code adds post/page/cpt-1/cpt-2 to the query loop block, you can change 'post', 'page', 'cpt-1', 'cpt-2'
to your own post type slugs.
add_filter( 'generateblocks_query_loop_args', function( $query_args, $attributes ) {
if (
! is_admin() &&
! empty( $attributes['className'] ) &&
strpos( $attributes['className'], 'advanced-query' ) !== false
) {
// pass meta_query parameter
$query_args[ 'post_type' ] = array('post', 'page', 'cpt-1', 'cpt-2');
}
return $query_args;
}, 10, 2 );
Adding PHP: https://docs.generatepress.com/article/adding-php/