Tile Palette grid is invisible or barely visible when using the Light Editor Theme

Steps to reproduce:

1. Create a new Unity project using the Universal 2D template
2. Make sure the Editor is using the Light Theme
3. Open the Tile Palette window (Window > 2D > Tile Palette)
4. Create a new 2D Sprite Triangle (Assets > Create > 2D > Sprites > Triangle)
5. Drag the 2D Sprite Triangle from the Project Browser into the Tile Palette window
6. Make sure the Grid is enabled in the Tile Palette window
7. Observe the Tile Palette window

Actual results: The grid is not visible or barely visible in the Tile Palette window

Expected results: The grid is clearly visible in the Tile Palette window

Reproducible with versions: 6000.0.3f1, 6000.0.54f1, 6000.1.15f1, 6000.3.0a3

Not reproducible with versions: 2022.3.64f1, 6000.0.2f1

Can’t test with versions: 6000.2.0b12 (due to [Internal link])

Tested on (OS): Windows 11, macOS Silicon Sequoia 15.5