Reproduction steps:
1. Open the attached “TerrainIssue.zip” project
2. Open the “SampleScene”
3. Select the “Terrain” GameObject from the Hierarchy
4. In the Inspector in the Terrain Component select the “Paint Terrain” button (Second from the left)
5. In the dropdown property select the “Smooth Height” option
6. Modify the value of the “Blur Direction” property
7. Observe the Console

Expected result: No warnings are thrown
Actual result: Warnings are thrown when the slider value is changed

Reproducible with: 2022.3.7f1, 2022.3.22f1
Not reproducible with: 2021.3.36f1, 2022.3.6f1, 2023.2.15f1, 6000.0.0b12

Reproducible on: Windows 11
Not reproducible on: no other environment tested

Notes:
- Full warning: “Saving has no effect. Your class 'UnityEditor.TerrainTools.SmoothHeightTool' is missing the FilePathAttribute. Use this attribute to specify where to save your ScriptableSingleton.
Only call Save() and use this attribute if you want your state to survive between sessions of Unity.
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)”
- Reproducible on a new project