Since the update of iOS 14 (iOS 14.5+ in particular), Facebook is unable to transfer the event data as Apple restricts the collection and upload of user information for users who refuse to be tracked. As a result, it generally discards these events and fails to reflect in attribution analysis of identified events and ad sets.
For example, Store A has 100 orders of which 50 orders were created by the iOS 14+ system; Assuming that 80% of users have turned off ad tracking and 20% of them agreed to be tracked, the data that the Facebook ad group will attribute is: 50 + 50 x 0.2 = 60 orders.
Compared with the 100 orders in the Admin, 60% of them can be attributed successfully, and the data difference is 40%.
SHOPLINE has reported the event to Facebook Pixel and server (Capi) and is actively communicating with Facebook to resolve this.