Reproduction steps:
1. Create a new 3D project
2. Attach Unity Editor to the second display
3. Load the "SampleScene" Scene
4. In the Hierarchy window create a new Empty GameObject
5. In the Inspector window click on the "Add Component" button
6. Observe the "Add Component" popup window

Expected result: The "Add Component" window appears under the "Add Component" button
Actual result: The "Add Component" window appears not under the "Add Component" button

Reproducible with: 2021.1.0b7, 2021.1.1f1, 2021.2.0a8
Not reproducible with: 2018.4.33f1, 2019.4.23f1, 2020.3.2f1, 2021.1.0b6, 2021.2.0a9, 2021.2.0a11

Notes:
- Only reproducible when using two displays
- Reproducible with these scaling combinations (first value shows Main display scaling and the second value - Second display scaling): (100%;175%), (125%;100%), (150%;100%), (150%;125%), (175%;100%), (175%;125%), (175%;150%), (200%;100%), (200%;125%), (225%;100%), (225%;125%), (225%;150%), (225%;150%), (225%;175%)