Timeline window is still dirty after pressing 'Save' in the prompt when closing a dirty Timeline

Steps to reproduce:

1. Create and open a new project
2. Open 'Window -> Sequencing -> Timeline' window
3. Select a GameObject and create a new Timeline asset
4. Add any track to the Timeline
5. Close the Timeline window
6. Click 'Save'
7. Repeat step 2 and select the previous GameObject
8. Observe the Timeline window

Actual results: The Timeline window is dirty

Expected results: The Timeline window is saved and clean

Reproducible with versions: 6000.0.0f1, 6000.0.82f1, 6000.3.23f1, 6000.5.10f1, 6000.6.0b10, 6000.7.0a5

Tested on (OS): Windows 11 Pro (25H2)

Notes:

• When saved through CTRL+S before step 5, the window later opens clean