How to reproduce:
1. Open the user attached project
2. Go to the Menu > Test > TestWindow
3. Observe the "TestWindow"

Expected result: "test Window" text is visible
Actual result: Text is not visible

Reproducible with: 2020.3.19f1, 2020.3.30f1, 2021.2.0b17, 2021.2.12f1, 2022.1.0a7, 2022.1.0a9, 2022.1.0b6, 2022.1.0b11
Not reproducible with: 2019.4.26f1, 2020.3.18f1, 2020.3.31f1, 2021.2.0b16, 2021.2.13f1, 2021.2.15f1, 2022.1.0a6, 2022.1.0a10, 2022.1.0b5, 2022.2.0a8

Notes:
- Not reproducible with Windows
- After pressing with right-click anywhere in the "TestWindow" the Text becomes visible
- After pressing with left-click anywhere in the "TestWindow" then focusing the Editor window and pressing with left-click again in the "TestWindowthe Text becomes visible

EDIT: Does not always reproduce, just keep reopening the TestWindow modal, it will sometimes not show the text until you hover the mouse over the window.