Render Graph Viewer's toolbar button is not rendered as a clean rectangle in its "Auto Update" state, stray pixels appear at the bottom-left corner

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Open Window > Analysis > Render Graph Viewer
3. Click the "Pause" button
4. Observe the "Auto Update" button

Actual results: Stray pixels appear at the bottom-left corner

Expected results: The "Auto Update" button is rendered as a clean rectangle

Reproducible with versions: 6000.3.22f1, 6000.5.9f1, 6000.6.0b9, 6000.7.0a5

Can’t test with versions: 6000.0.0f1, 6000.0.82f1 (due to a different UI layout)

Tested on (OS): Ubuntu 24.04, MacOS Silicon Tahoe 26.5.1