Reproduction steps:
1. Open the attached project "ReproProj"
2. In the menu bar, click “File > Build Profiles”
3. Add “Scenes/SampleScene” in the Scene List
4. Select “Development Build“, “Autoconnect Profiler“, and “Deep Profiling Support“
5. Click “Build And Run“
6. Open Memory Profiler (Window > Analysis > Memory Profiler)
7. Take a Snapshot
8. Select Snapshot
9. Open “All Of Memory“ tab
10. Search for “Cube“
11. Expand “Managed Objects” and “System.String“

Expected result: 0 "Assets/Cube.prefab" string entries
Actual result: Multiple "Assets/Cube.prefab" string entries persist

Reproducible with: 2.6.0 (6000.0.44f1)
Not reproducible with: 2.7.0 (6000.0.44f1), 2.7.2 (6000.0.44f1, 6000.2.4f1, 6000.3.0b1)

Reproducible on:
Windows Standalone Player

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested