50% of your ad spend goes to unprofitable products. Performance Max (PMax) meets targets through averaging the performance of all products in a campaign (e.g. both low and high ROAS products will be promoted, as long as the end result hits the goal).
It’s more effective to split your products into separate, performance-based buckets: by grouping profitable products into one campaign and unprofitable products into another, you ensure that Google bids high and low on the right ones.