Edges are softened when a RectMask2D with 0 softness is used

How to reproduce:

1. Open the attached project “IN-152255”
2. Open the “Assets/Scenes/RectMask2D_ClipEdgeAA“ scene
3. Enter Play Mode
4. Observe the Game View

Actual result: Edges on the left most square are not white
Expected result: Edges on all squares are white

Reproducible with: 6000.0.0f1, 6000.0.82f1, 6000.3.23f1, 6000.5.11f1, 6000.6.0f1, 6000.7.0a6

Reproducible on: macOS 26.5.2 (M4 Max)
Not reproducible on: No other environments tested