How to reproduce:

1. Create and open a new project
2. Create a new Canvas → Image GameObject
3. Set “UI Scale Mode“ to “Scale With Screen Size“ on the Canvas Scaler Component
4. Make a Prefab of the Canvas GameObject
5. Select the Prefab in the Project Tab
6. Change the Scale on the X axis to any value
7. Double-click the Prefab in the Project Tab to open it in Prefab Mode
8. Make any change to the prefab (not on scale) to force a serialization
9. Select the Canvas Prefab in the Project tab again
10. Observe the Scale on the X axis in the Inspector

Actual result: 0 is displayed
Expected result: the old value is displayed

Reproducible in: 2023.1.0a1, 6000.0.68f1, 6000.3.10f1, 6000.4.0b10, 6000.5.0a7

Reproduced on: Windows 11 Pro (25H2)
Not reproduced on: No other environment tested

Notes:
- This is reproducible only if Canvas Scaler is editable in Prefab Mode (e.g., if the Width/Height, Anchor, and Pivot values are non-default, the Canvas Scaler Component will not be editable (because of non-root Canvas), and in turn the bug won’t occur)
- Reproducible with all Position, Rotation, and Scale transforms
- The reporter states that this correlates to the Game view being closed, however when testing locally, the issue was observed with the Game view open as well