I am using AppsFlyer OneLink for deep linking and need to confirm whether custom query parameters appended to a OneLink long URL persist during deferred deep linking.

What I Have Tested:

• I appended a custom query parameter to a OneLink long URL like this:

• When the app is already installed, the parameter is successfully passed to the app.
• However, in deferred deep linking (installing the app after clicking the link), the parameter did not persist—it was lost when retrieving deep link data.
• I tested this using a developer install (direct install from a build), not through an actual App Store or Play Store flow, so I am unsure if this is expected behavior or just a limitation of my test setup.

My Question:

1. Are additional query parameters from a OneLink long URL retained in deferred deep linking?
2. Does AppsFlyer only retain parameters predefined in the short link itself when deep linking after install?
3. Is there a way to ensure query params persist without using the OneLink API (since it is a premium feature)?

Any insights or workarounds would be greatly appreciated!