How to reproduce:
1. Create a new Unity project and import the attached "New Shader Graph"
2. Create the new UI Document and open it
3. Add a Visual Element
4. In the UI Builder's Inspector, go to Material and open the object picker
5. Select the "New Shader Graph" and observe the results
Expected results: The "New Shader Graph" can't be selected because it is not compatible with UITK
Actual results: Validation warnings and the message box are shown post-factum
Reproducible with: 6000.0.71f1, 6000.3.12f1, 6000.4.2f1, 6000.5.0b2, 6000.6.0a3
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
Note: In similar situations across the Editor, non-compatible objects are sorted out