How to reproduce:
1. Open the attached “IN-118764” project
2. In the Project window, select “TestPrefab-Variant” prefab Asset
3. In the Inspector window, observe the values of linear and angular drag
4. Upgrade the project to the latest Unity branch version
5. In the Project window, select “TestPrefab-Variant” prefab Asset
6. In the Inspector window, observe the values of linear and angular damping

Expected result: Prefab variant keeps the values of linear and angular drag
Actual result: Prefab variant keeps the values of the parent prefab’s linear and angular damping

Reproducible with: 6000.0.11f1, 6000.0.59f2, 6000.2.7f2, 6000.3.0b5, 6000.4.0a2
Not reproducible with: 6000.0.10f1(413673acabac)

Reproduced on: macOS 15.6 (M1)
Not reproduced on: No other environment tested

Workaround:
1. Upgrade the project to 6000.0.10f1(413673acabac)
2. Open/Load the project
3. Upgrade the project to the version of your choice