Reproduction steps:
1. Create a new project
2. Select any GameObject in Hierarchy
3. Create any GameObject (e.g. right-click > 3D Object > Cube)
4. Observe newly created GameObject in Hierarchy

Actual result: New GameObject is created as a child of the currently selected GameObject
Expected result: New GameObject is not a child of any GameObject

Reproducible with: 6000.5.0a5
Not reproducible with: 6000.0.66f1, 6000.3.5f1, 6000.4.0b5, 6000.5.0a4

Reproduced on: macOS Sequoia 26.2 (M4)
Not reproduced on: Windows 11

Note: Issue is not reproducible when creating GameObject via GameObject menu