PowerPack Content Grid - Display taxonomy term thumbnail in post as a fallback image

code.php

add_filter( 'pp_post_image_settings_data', function( $data, $settings ) {
	global $post;
	
	if ( false !== strpos( $data['photo_src'], 'placeholder.jpg' ) ) {
		$terms = get_the_terms( $post->ID, 'category' ); // Here "category" is the post taxonomy slug.

		if ( ! is_wp_error( $terms ) && ! empty( $terms ) ) {
			$term = $terms[0]; 
			
			$term_thumb_id = get_term_meta( $term->term_id, 'taxonomy_thumbnail_id', true );
			
			if ( '' !== $term_thumb_id ) {
				$obj_term_thumb = wp_get_attachment_image_src( $term_thumb_id, 'medium' );
				
				$data['photo_src'] = $obj_term_thumb[0];
			}
		}
	}

	return $data;
}, 10, 2 );