Changes in Timeline aren't discarded when closing the window and pressing 'Discard' in the prompt

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 'Discard'
7. Repeat step 2 and select the earlier GameObject
8. Observe the Timeline window

Actual results: The added track remains

Expected results: The added track is discarded

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:

• Reproduces also when closing the Editor as a whole