Only load in specific custom post types

Hi, very nice plugin.
My theme takes care of modal pop ups for images in single posts so I don’t want WP Featherlight be loading there. Instead, I want to load it for custom post types.

I tried

function remove_featherlight_at_singles() {
    if (is_single() ) {
        add_filter( 'wp_featherlight_load_css', '__return_false' );
        add_filter( 'wp_featherlight_enable_packed_js', '__return_false' );
    }
}
add_action('wp_head', 'remove_featherlight_at_singles');

but it didn’t work. The result is on single posts I get 2 modal windows (one from WPFL and one from the theme).

Is there a way to either disable loading on single posts, or load it only at specific CPTs?

thanks

https://www.ads-software.com/plugins/wp-featherlight/