High CPM can stem from several issues especially when you set up the ads. First, low relevance scores can increase costs. If your ads are not engaging or relevant to the audience, Facebook charges more. Second, competition plays a significant role. If many advertisers target the same audience, CPM rises due to demand. Third, the type of campaign matters. Conversion campaigns usually have higher CPMs than awareness campaigns. Lastly, technical problems like low-quality images or broken links can also hurt performance. Monitoring these factors helps identify issues and improve your CPM effectively.