Reproduction steps:
1. Open the attached “Spline.zip” project
2. Open the “SampleScene”
3. In the Hierarchy click on the "Target" GameObject
4. Observe the GameObject's Rotation property
5. Enter the Play mode
6. Exit the Play mode while the GameObject is still selected
7. Observe the GameObject's Rotation property

Expected results: "Target" GameObject Rotation remains the same
Actual result: "Target" GameObject Rotation on the Y-axis gets set to 90 degrees

Reproducible with: 2.5.1 (2021.3.34f1, 2022.3.17f1, 2023.2.6f1, 2023.3.0b3), 2.5.2 (2021.3.34f1, 2022.3.17f1, 2023.2.6f1, 2023.3.0b3)

Reproducible on: Windows 10, Windows 11
Not reproducible on: no other environment tested

Notes:
- After exiting the Play mode, Scene shows up with un-saved changes
- Affects both the prefab and the original GameObject
- Also reproducible with 3D GameObjects