Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: 1.103.0-insider
• OS Version: Ubuntu 24.04

Steps to Reproduce:

1. Go to https://vscode.dev on the latest version of Firefox
2. Create a new unamed test file
3. Right click on the tab title, then Copy in new window
4. Open the command picker, type color theme then select Preferences: Color Theme
5. While the external window is still visible, change the theme to a white theme
6. In the external window, the theme is partially applied and looks completely broken