Performance Max (PMax) is Google's all-in-one automated campaign type. It finds customers across YouTube, Display, Search, and Gmail. It is powerful, but dangerous.
The Danger: Brand Cannibalization
Left unchecked, PMax loves to spend budget on "Brand Search"—bidding on your own name. This inflates your results (because people searching your name were likely going to buy anyway) while failing to find new customers.
The Fix: Brand Exclusions
You must rigorously add your brand name as a "Negative Keyword" or distinct "Brand Exclusion" list within PMax settings. This forces the AI to hunt for cold traffic—people who don't know you yet. That is where true growth happens.