People get confused about iOS organic installs and how much of that bucket is really misattributed paid. It is easier to check than it looks. Two reports will tell you.
1. App Store Connect
Analytics, Downloads, grouped by source.
App Referrer is where clicks from Meta land. That part is measurable, and it is the part everyone already knows.
The part people miss is App Store Search. A lot of paid social users never install from the click. They see the ad, then go and search the app name a day later. Those installs land in search, not in referrer.
Watch whether App Store Search rises and falls with spend. If it moves with the budget, a share of what gets called organic is paid.
If the app ranks well or already has brand demand, search will be high regardless. Control for that before reading the result.
2. The MMP against Meta
Plot daily organic installs against daily paid installs, one dot per day.
Genuinely organic traffic sits flat against spend. If the cloud slopes, that slope is the leak, and the intercept is roughly the real organic baseline.
Then run the identical chart for Android. The install referrer still works there, so it should come out close to flat. iOS sloping while Android stays flat points at ATT. Seasonality would move both.
One account, 103 days since 1 May 2026. iOS slope 0.277: about 28 of every 100 paid iOS installs reappear as organic. Android slope 0.059, the normal halo of a paid campaign.
Pull the reports and check it for yourself.