Reproduction steps:
1. Open the attached “IN-97090” project
2. Open the “Scenes/Example Scene” Scene
3. Select the “Hero” GameObject in the Hierarchy window
4. Observe the “Items” value under “Inventory” component in the Inspector window
5. Enter the Prefab Mode for “Hero” Prefab
6. Observe the “Items” value under “Inventory” component in the Inspector window

Expected result: References to external subassets remain unchanged and correctly point to their original targets
Actual result: References to external subassets are redirected to the prefab's own subasset, causing permanent data corruption

Reproducible with: 2022.3.60f1, 6000.0.45f1, 6000.1.0b13, 6000.2.0a8

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