How to reproduce:
1. Create a new Unity project
2. In the Hierarchy, right-click -> UI (Canvas) -> Canvas
3. In the Inspector, under the "Rect Transform" Component, click the "?" button
4. Observe the results

Expected results: The documentation is opened
Actual results: The documentation is missing

Reproducible with: 6000.4.0a1, 6000.4.0b4, 6000.5.0a5
Not reproducible with: 6000.0.64f1, 6000.3.3f1

Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested

Note: Not considering it a regression since it never appeared in 6000.4