Making relatd posts

I’m modifying a function that gets posts related by cat and tag to the current post. I’m having trouble after modifying it’s still not showing what I want.

Original

public static function get_related_posts($max_posts = 20){
		$my_posts = array();
		
		$post_id = get_the_ID();
		
		$tags_string = '';
		$post_tags = get_the_tags();
		if ($post_tags) {
			foreach ($post_tags as $post_tag) {
				$tags_string .= $post_tag->slug . ',';
			}
		}
		
		$query = array(
						'exclude' => $post_id,
						'numberposts' => $max_posts,
						'tag' => $tags_string
					 );
					 
		$get_relateds = apply_filters('essgrid_get_related_posts', $query, $post_id);
		$tag_related_posts = get_posts($get_relateds);		
		
		
		if(count($tag_related_posts) < $max_posts){
			$ignore = array();
			foreach($tag_related_posts as $tag_related_post){
				$ignore[] = $tag_related_post->ID;
			}
			$article_categories = get_the_category($post_id);
			$category_string = '';
			foreach($article_categories as $category) { 
				$category_string .= $category->cat_ID . ',';
			}
			$max = $max_posts - count($tag_related_posts);
			
			$excl = implode(',', $ignore);
			$query = array(
							'exclude' => $excl,
							'numberposts' => $max,
							'category' => $category_string
						 );
						 
			$get_relateds = apply_filters('essgrid_get_related_posts_query', $query, $post_id);
			$cat_related_posts = get_posts($get_relateds);
			
			$tag_related_posts = $tag_related_posts + $cat_related_posts;
		}
		
		foreach($tag_related_posts as $post){
		
			$the_post = array();
			
			if(method_exists($post, "to_array"))
				$the_post = $post->to_array();
			else
				$the_post = (array)$post;
			
			if($the_post['ID'] == $post_id) continue;
			
			$my_posts[] = $the_post;
		}
		
		return apply_filters('essgrid_get_related_posts', $my_posts);
	}

stripping out all tag related code

	public static function get_related_posts($max = 20){
		$my_posts = array();
		
		$post_id = get_the_ID();
		
		$article_categories = get_the_category($post_id);
		$category_string = '';
		foreach($article_categories as $category) { 
			$category_string .= $category->cat_ID . ',';
		}
		
		$query = array(
						'exclude' => $post_id,
						'numberposts' => $max,
						'category' => $category_string
					 );
					 
		$get_relateds = apply_filters('essgrid_get_related_posts_query', $query, $post_id);
		$cat_related_posts = get_posts($get_relateds);
			
		
		foreach($cat_related_posts as $post){
		
			$the_post = array();
			
			if(method_exists($post, "to_array"))
				$the_post = $post->to_array();
			else
				$the_post = (array)$post;
			
			if($the_post['ID'] == $post_id) continue;
			
			$my_posts[] = $the_post;
		}
		
		return apply_filters('essgrid_get_related_posts', $my_posts);
	}

But I’m getting everything returned. I’m not a dev. I don’t even know how to start debuggin. Do you see what’s wrong?