How to reproduce:
1. Open the attached “graphs.zip” project
2. Open “New Shader Graph” Shader Graph
3. Add any Node
4. Enter play Mode
5. Exit Play Mode and observe the Shader Graph

Expected result: The added Node is in the Shader Graph
Actual result: The added Node is not in the Shader Graph

Reproducible with: 2022.2.2f1, 2022.2.21f1, 2022.3.10f1, 2023.1.14f1, 2023.2.0b10, 2023.3.0a6
Not reproducible with: 2021.3.30f1, 2022.2.1f1

Reproduced on: macOS 13.5.2 (Intel)
Not reproducible on: No other environment tested

Note: if saving Shader Graph before entering Play Mode, then the issue is not reproducible