Everything in GA4 is an event, which makes it flexible but different enough that older reports and integrations often need rebuilding. It commonly runs alongside a CDP like Bloomreach, and the two identify users differently, so their numbers rarely match exactly.

In practice

Treat GA4 as your measurement and reporting layer, not your activation layer. When GA4 and your CDP disagree, reconcile them deliberately, for example via the GA4 client ID, rather than expecting them to line up on their own.