How to reproduce:
1. Open the attached “Project_xyz” project
2. Navigate to Assets -> Scenes -> System Scene -> Lobby
3. Enter Play mode
4. In the Hierarchy expand UI Group GameObject and enable the Log Canvas GameObject
5. In Game view press the Book icon in the top right corner
6. Press and drag bottom right of the book
7. Observe Game view

Actual result: UI Mask Component does not correctly render the page
Expected result: UI Mask Component renders the page correctly

Reproducible with: 6000.0.54f1(4c506e5b5cc5), 6000.0.64f1, 6000.2.15f1, 6000.3.1f1, 6000.4.0b1, 6000.5.0a3
Not reproducible with: 6000.0.53f1

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Note: Changing the Canvas Render Mode to Screen Space - Overlay fixes the issue