How to reproduce:
1. Create a new Unity project
2. In the Scene view click on any dropdown of the control bar
3. Observe the dropdown

Expected results: The dropdown is under the clicked option
Actual results: The dropdown is far to the left of the clicked option

Reproducible with: 2021.2.0a15, 2021.2.0a16
Not reproducible with: 2018.4.33f1, 2019.4.26f1, 2020.3.7f1, 2021.1.5f1, 2021.2.0a14

Note:
- In step 2, clicking on the "Gizmos" dropdown will not reproduce the issue