The new iOS effectively killed retargeting ads especially from Facebook. A friend of mine said sales basically disappear from retargeting ads. Not only retargeting is killed, look alike audience also went down the drain.
Thus self hosted landing pages need to work hard to really sell. There's no easy way to try again or getting more prospects.
However, eCommerce platforms can easily do retargeting and finding look alike audience among their millions of users. They already have the user data and can follow the user from website to apps.
Granted, the audience size is smaller but they have higher probability to convert. They already signed up to shop so the intention to buy is high.
Perhaps this will mean eCommerce platforms have significantly higher conversion rate compared to self hosted eCommerce solution. If so, it will shift the market control from Facebook to eCommerce platforms.