Reproduction steps:
1. Create a new project and import AR-related packages
2. Use the code below to reproduce the issue
internal void UpdateEyes()
{
if (leftEye == null && rightEye == null && fixationPoint == null)
{
leftEye = Instantiate(new GameObject(), transform).transform;
rightEye = Instantiate(new GameObject(), transform).transform;
fixationPoint = Instantiate(new GameObject(), transform).transform;
}
UpdateTransformFromPose(leftEye, sessionRelativeData.leftEyePose);
UpdateTransformFromPose(rightEye, sessionRelativeData.rightEyePose);
fixationPoint.localPosition = sessionRelativeData.fixationPoint;
}

Expected result: Only instantiate needed objects and destroy them with an ARFace without leaving empty GameObjects in the scene
Actual result: Each time an ARFace is added three new GameObjects are created in the scene and never destroyed

Reproduces based on user information: 2019.4.24f1 (ARFoundation 4.1.7, ARKit 4.1.7, ARCore 4.1.7)