The debate about Performance Max versus Standard Shopping campaigns has produced more heat than light. The honest answer depends on the account, the catalogue and the measurement setup. A structured framework for making the right call for your specific situation.
Advantage+ Shopping campaigns are Meta's version of Performance Max: powerful when structured correctly, capable of spending inefficiently when left to their own devices. A systematic audit checklist for accounts that have been running ASC for three months or more.
Most Performance Max underperformance is a feed problem. The campaign structure and bidding get the attention, but it is the product data quality, title logic and custom labels that determine what gets served, to whom and at what margin.