“Graph Processing Pending” pop-up text is not visible in Graph Toolkit window when Editor Theme is set to Light

Reproduction steps:
1. Create a new project and make sure Editor Theme is set to Light (Edit > Preferences… > General > Editor Theme)
2. Drag and drop the attached “MySimpleGraph.cs” file to the Assets folder
3. Create > Graph Toolkit Samples > Simple Graph
4. Double-click on the newly created Graph Asset to open Graph window
5. Make a change in the window to trigger “Graph Processing Pending” pop-up (e.g. Right-click and select “Create Sticky Note” option)
6. Observe Graph window

Actual result: Black rectangle briefly appears in the window with no visible text
Expected result: Black rectangle with “Graph Processing Pending” text briefly appears in the window

Reproducible with: 6000.3.12f1, 6000.4.1f1, 6000.5.0b1, 6000.6.0a1

Reproduced on: Windows 11