Incorrect UI document size and positioning of element in a worldspace UI document when 'align self' is set to 'center' on template

Reproduction steps:

1. Open the attached “IN-140449” project
2. Open the SampleScene
3. Enter Play Mode
4. Observe the “BoxCollider” Component on the “Worldspace UI” GameObject, note its size
5. Press the “Add Child” onscreen button
6. Press the “Set align-self: center” button
7. Observe the “BoxCollider”, compare its size to step 4

Actual result: The BoxCollider’s size increases from 4x3 to 4.15x3
Expected result: The BoxCollider’s size does not increase

Reproducible with: 6000.3.14f1, 6000.3.0a3, 6000.4.4f1, 6000.5.0b3, 6000.6.0a3
Not reproducible with: 6000.0.73f1, 6000.3.0a2

Reproducible on: macOS 26.3.1 (by reporter), macOS 26.4.1
Not reproducible on: No other environments tested