Reproduction steps:
1. Open the user’s attached project “IN-6321_Unity3DUrpLtsProjekt_PlainSimpleAndThin”
2. Build the project
3. Download “IN-6321_UnityEmbeddedInWindowsForms” and extract it
4. Go to \\IN6321_UnityEmbeddedInWindowsForms\\UnityEmbeddedInWindowsForms
UnityBuild
5. Delete the “UnityBuild” folder’s contents and place built Player files
6. Open \\IN-6321_UnityEmbeddedInWindowsForms
UnityEmbeddedInWindowsForms.sln
7. Press “Start”
8. Click the "Start and embed” button in the Windows form

Expected result: The Player is played in Windows Form without errors
Actual result: “GetWindowRect failed: Invalid window handle.” error

Reproducible with: 2021.2.0a16, 2021.2.19f1, 2021.3.6f1, 2022.1.10f1, 2022.2.0b2, 2023.1.0a4
Not reproducible with: 2020.3.37f1, 2021.2.0a15

Reproducible on: Windows 10