Repro steps:
1. Create a default VFX
2. Create a default VFX Shader Graph, open it, add a color to blackboard, plug it in the Base Color slot, and save the graph
3. Open the VFX and assign the Shader Graph. Save the VFX and close it.
4. Press Ctrl+S to save everything again (just in case)
5. Exit Unity
6. Commit the files to version control
7. Open Unity again
8. Open the ShaderGraph aset and change the graph flow (i.e. add a Multiply node between Color and Base Color, img attached)
9. Save the SG, press Ctrl+S to save everything again
10. Take a look in version control and observe that the VFX file shows as modified with it's default texture slot being removed

Expected outcome:
No change on the VFX side when making changes in ShaderGraph which do not affect exposed properties.

Notes:
- Video attached
- It seems to only repro if there's an exposed property in SG
- The editor restart seems to have an affect on the outcome