How to reproduce:
1. Create a new project
2. Create a Lit Shader Graph (Create → Shader Graph → Lit Shader Graph)
3. Open the created Shader Graph
4. Add a “UV” node
5. Add two “Swizzle” nodes
6. Connect both nodes to the “UV” node
7. Set the “Swizzle” nodes' mask values to “XY” on one and “xy” on the other
8. Observe the Shader Graph

Actual result: The swizzle with the mask value of “XY” is black
Expected result: Both swizzles produce the same results

Reproducible with: 6000.3.4f1, 6000.4.0b4, 6000.5.0a4
Not reproducible with: 6000.0.65f1, 6000.5.0a3

Reproducible on: MacOS Sequoia 15.7.3 (M1 Max)
Not reproducible on: No other environments tested