Question about flowering nutrients

From a fellow grower: I have a question about some nutrients I got recently. In the grow Bible it specifies that flowering plants need high phosphorous content nutrients. However, when I received the flowering nutrients from ILGM its high in potassium. I’ve always heard that it is actually the phosphorous that is needed for flowering but if thats the case this whole flowering nutrients pack is worthless. Can you please clarify this for me?