Full Answer
View-through = saw ad, didn't click, converted later. Facebook counts, GA4 doesn't. Number mismatch.
Cherry Seed
What are view-through conversions?
attribution model
conversion tracking
channel grouping
Quick Answer
User sees ad but doesn't click, then converts later. Facebook counts these (1-day view window), GA4 doesn't. Explains why Facebook conversion numbers often exceed GA4—Facebook sees view-influenced conversions invisible to GA4.