UI Toolkit Dropdown input consumed when uGUI EventSystem is also in the scene

Reproduction steps:

1. Open the attached project
2. Open the “/Assets/Scenes/SampleScene.unity” Scene
3. Enter the Play Mode
4. Click on the Dropdown field and observe its behavior

Expected result: Dropdown menu is shown
Actual result: Dropdown menu isn’t shown

Reproducible with: 2022.1.0a6, 2022.1.10f1, 2022.2.0a5
Not reproducible with: 2021.3.6f1, 2022.1.0a5, 2022.2.0a6, 2022.2.0b2, 2023.1.0a4
Could not test with: 2019.4.39f1, 2020.3.37f1 (Panel Settings Assets are not implemented)

Reproducible on: Windows 10 (21H2), M1 MacOS 12.4 (21F79)

Notes:

• Disabling or removing the EventSystem GameObject fixes the issue
• Using the M1 Mac, the issue is reproducible on both Intel and Apple Silicon Editors