How to reproduce:
1. Create a new Unity project
2. In the Hierarchy, right-click -> 3D Object -> Terrain
3. In the Inspector, switch to the "Paint Terrain" mode
4. In the Scene view, navigate to the brush Overlay with the "Opacity" and "Size" settings
5. In the Inspector, navigate to the brush "Opacity" 
6. Compare the values between the Scene view and Inspector

Expected results: The values are in the same numerical range
Actual results: The range in the Scene view is 0 to 1, in the Inspector 0.2 to 100

Reproducible with: 6000.0.58f1, 6000.2.5f1, 6000.3.0b2

Reproducible on: macOS Sequoia 15.6 (M1)
Not reproducible on: No other environment tested

Note: The Opacity values in the Scene view seem to be the correct way to represent Opacity