How to reproduce:
1. Create a new HDRP project
2. Create Lit Shader Graph and open it
3. Set Surface Type to Transparent in Graph Inspector
4. Drag Edge from Base Color port of Fragment Stack and once node menu opens, add color node

Expected result: Shader Graph does not recompile
Actual result: Shader Graph recompiles

Reproducible with: 2021.2.0a11(12.0.0)

Notes:
- Couldn't reproduce on URP
- Couldn't reproduce with opaques
- Sometimes it happens when nothing is changed (for instance, just refocusing windows), recompilation sometimes takes up to 15 seconds