Regression: Vertical tabs no longer collapse in fullscreen (F11) after latest Edge update

After the latest Microsoft Edge update, the vertical tab sidebar no longer collapses when entering fullscreen mode (F11).

Previously, when fullscreen was enabled, the vertical tabs would automatically collapse or hide, allowing the webpage to use the full screen space. Now the vertical tab bar remains visible, reducing usable screen area.

Steps to reproduce:

1. Enable Vertical Tabs in Microsoft Edge
2. Open any website
3. Press F11 to enter fullscreen mode
4. Observe that the vertical tab sidebar remains visible

Expected behavior:
Vertical tabs should collapse or automatically hide in fullscreen mode, as they did in earlier versions.

Actual behavior:
The vertical tab sidebar stays visible during fullscreen instead of collapsing.

Additional testing:

• Tested in a Guest profile (fresh profile with default settings); issue still occurs
• Happens across different websites
• Restarting Edge does not fix the issue

Edge version:
145.0.3800.58 (Official build) (64-bit)