Player window does not scale resolution/aspect ratio when going from windowed to fullscreen mode by ALT + ENTER

Reproduction steps:

1. Open the user attached project
2. Press File → Build And Run
3. Scale down the Player window horizontally
4. Press ALT + ENTER

Expected result: The player window resizes to fill the whole screen, no black bars
Actual result: The player window does not resize to fill the whole screen, black bars

Reproducible with: 2020.3.39f1, 2021.1.28f1, 2021.2.0b9
Not reproducible with: 2021.2.0b10, 2021.3.9f1, 2022.1.14f1, 2022.2.0b6, 2023.1.0a8

Reproduced on: Windows 10

Additional info:

This issue was addressed in 2021.20b10 release as an "improvement" (not a customer reported bug):

Windows: Alt + Enter now defaults to native resolution rather than the resolution that the window was in windowed mode. This makes the image more crisp and reduces the chance of letterboxing.