Every quarter I get the same message: the ad platform says 400 conversions, GA4 says 240, and the CRM says 180. Nobody is lying – they are all measuring different things.
Three different clocks
Ad platforms report on the day of the click. GA4 reports on the day of the conversion. Your CRM reports on the day the deal was accepted. A 30-day sales cycle will spread one purchase across three different months.
What to do about it
Pick one source of truth for money – almost always the CRM or the payment processor – and treat the platforms as directional signals for optimisation only. Then import offline conversions back so the bidding algorithms learn from real revenue.