How to reproduce:
1. Create a new Unity project
2. In the Hierarchy, right-click -> UI (Canvas) -> Text (TextMeshPro)
3. In the Inspector, click Add Component -> Layout Element
4. Enable any field and enter the custom value
5. Disable the field
6. Reenable the field and observe the value
Expected results: The previous custom value is preserved
Actual results: The previous custom value is not preserved
Reproducible with: 6000.0.76f1, 6000.3.15f1, 6000.4.8f1, 6000.5.0b9, 6000.6.0a7
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
Note: Preserving the value is a standard behaviour in the Editor