How to reproduce:
1. Open the attached “memoryprofiler_issue“ project
2. Open the Build Settings (File → Build Settings) and ensure “Development Build“ is enabled
3. Press “Build And Run”
4. While the Player is running, open the Memory Profiler (Window → Analysis → Memory Profiler)
5. In the menu bar of the Memory Profiler, select the “Target Selection” (default value is “Editor”) drop-down and choose the recently opened instance of the Player
6. press the “Capture New Snapshot” button
7. Select the newly generated snapshot from the tab on the left side
8. Select the “All Of Memory” tab
9. Navigate to “Native → Unity Subsystems → Unknown”

Expected result: Only a small amount of memory is allocated under “Unknown”
Actual result: A significant amount of memory is allocated under “Unknown” (~1GB+)

Reproducible in: 1.0.0 (2022.3.12f1, 2023.2.0b16), 1.1.0 (2022.3.25f1, 2023.2.19f1, 6000.0.0b15)
Could not test with: 0.7.1-preview.1 (2021.3.37f1) (feature does not exist)

Reproducible on: Windows 10, Windows 11
Not reproducible on: No other environments tested

Note: In 1.0.0, the MaterialPropertyBlocks' allocated memory is displayed under “Native Memory → Reserved”