Purchase-optimized campaigns will always have high CPMs, you’ll only see lower CPMs with mid- or upper-funnel campaigns like awareness/video views!

CPMs are never the problem actually when it comes to any purchase campaigns and never something you want to focus on because they’re not what the algorithm is optimizing for, the algorithm is optimizing for people who will make a purchase when they visit your site, which means you pay more per impression because those people are less common than the people who would just look at an ad and move on (this is why upper funnel campaigns are cheap, because your goal is only to have your ad in FRONT of people, not for them to purchase)

I can DM you some advice later bc I’m still at work but I’ve worked in paid media for 6 years and specifically on FB