Why do Instagram link clicks not match my GA4 sessions?

Instagram link clicks and GA4 sessions measure different points in the trip, so they usually won’t match exactly. A click can happen without the landing page ever loading far enough for GA4 to start a session, and GA4 also depends on your tag being allowed to run. Missing or stripped UTM parameters, redirects, ad blockers, and consent choices can make the visit show up as Direct or not get tracked the way you expect. I’d start by using one full UTM-tagged URL in Instagram, then compare GA4’s Traffic acquisition report using Session manual source / medium and the same date range and timezone. Treat the difference as a tracking funnel to debug, not as proof that either dashboard is wrong.