Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Create a new Lit Shader Graph (Assets > Create > Shader Graph > URP > Lit Shader Graph)
3. Press Space in Shader Graph window, add Custom Function Node and select it
4. In Graph Inspector > Node Settings > press “+” in “Outputs” list
5. Expand Node preview window
6. Press undo with keyboard shortcut
7. Press redo with keyboard shortcut
8. Observe the Node preview window
Actual results: The Custom Function Node preview renders nothing, "x" and "^" buttons are on top of each other
Expected results: The Custom Function Node preview renders as a magenta/black checkerboard
Reproducible with versions: 6000.0.78f1, 6000.3.20f1, 6000.5.4f1, 6000.6.0b4, 6000.7.0a2
Tested on (OS): Ubuntu 24.04, macOS Tahoe 26.5.1 (M1)