Repro steps.

1. Default scene (SampleScene) should be open.
2. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is not loaded.
3. Open scene SampleSceneWithPrefab
4. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is loaded.
5. Open scene SampleScene
6. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is not loaded.

The texture is unloaded as expected in workflow above.

Problematic workflow

1. Default scene (SampleScene) should be open.
2. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is not loaded.
3. Preview the prefab PrefabWithTexture
4. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is loaded.
5. Exit preview
6. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is loaded.
7. Open scene SampleSceneWithPrefab
8. Open scene SampleScene
9. Take memory snapshot. Notice Texture "Screenshot 2023-09-13 091306" is loaded.

In this workflow, "Screenshot 2023-09-13 091306" remains loaded.