Refinement of AR Implementation in Flutter App

We are developing an exclusive iOS application built with Flutter. The core feature revolves around displaying 3D objects (spheres) in real space based on specific geographic coordinates (Latitude & Longitude).
Currently, the app is facing a critical issue: when using ⁠ARWorldTrackingConfiguration⁠, the 3D objects spawn near the user or shift their positions relative to the user's movement. They do not stay fixed to their assigned real-world GPS coordinates, and they reset/spawn relative to the camera every time the app is reopened.
Required Tasks:
1. Refactor the AR implementation using ⁠arkit_plugin⁠ (or an equivalent native iOS wrapper for Flutter).
2. Implement a mathematical approach (e.g., Haversine Formula) to calculate the distance and bearing between the user's current GPS location (⁠CoreLocation⁠) and the object's targeted coordinates, translating this into precise local AR space anchors (X, Y, Z).
3. Ensure absolute geographic persistence: if a user closes the app, walks away, and reopens it, the object must remain strictly anchored to its original real-world location and not "follow" the user's camera view.
4. Enable proper Plane Detection to prevent objects from floating awkwardly, and implement a Distance Threshold check to prevent nearby objects from overlapping or clustering together.
Freelancer Requirements:
Proven experience working with ARKit and Flutter AR integrations.
Strong understanding of combining geospatial data/sensors (⁠GPS⁠ and ⁠Compass⁠) with AR tracking environments.
Must own a physical iPhone to locally test and debug the AR tracking before delivery, ensuring absolute accuracy.
This English version uses precise industry terms (⁠Geospatial persistence⁠, ⁠Plane Detection⁠, ⁠Distance Threshold⁠) that will instantly signal to elite AR developers exactly what needs to be fixed.