It's not the number of colours but the number of products in the "All" collection - https://shop.emeralderin.com/collections/all

So in the code in order to find the other products with the tag, we grab 200 products from that collection, and search through them, to look for the tags.

Which is why as mentioned in the article we typically use a vendor or product type based collection to ensure this is less than 200 products, so we can search for all products with the tag.