Bugzilla

Affected Version: 
Nightly - 140.0a1/20250514211700

Description:
Opening a new tab in the main Firefox instance, loading https://www.wikipedia.org/ and adding it to the taskbar will show the “Back” button actionable in the PWA window. Clicking the back button from the PWA window will show the new tab page, meaning the navigation history of before the PWA window was created is preserved.

Steps to reproduce:
1. In the main Firefox instance, open a new tab and navigate to https://www.reddit.com/
2. On the Reddit page, from the left sidebar, select a topic. For example, Games -> Action Games. Page is navigated to https://www.reddit.com/t/action_games/
3. From the same page, navigate to https://www.wikipedia.org/ and then open it in a PWA window
4. In the PWA window, notice that the “Back” button is actionable
5. Click the “Back” button several times
6. Notice that from the Wikipedia page, users can go back to both Reddit pages and ultimately to the new tab page from where the whole process was started i.e. navigation history is preserved from before the PWA window was created

Actual results:
Navigation history is preserved for PWA windows when created.

Expected:
There should be no navigation history from before the PWA window was created, the page that was opened in said window being the first item in the navigation history of the PWA window.

Affected Version: 
Nightly - 140.0a1/20250514211700

Description:
Opening a new tab in the main Firefox instance, loading https://www.wikipedia.org/ and adding it to the taskbar will show the “Back” button actionable in the Taskbar Tabs window. Clicking the back button from the Taskbar Tabs window will show the new tab page, meaning the navigation history of before the Taskbar Tabs window was created is preserved.

Steps to reproduce:
1. In the main Firefox instance, open a new tab and navigate to https://www.reddit.com/
2. On the Reddit page, from the left sidebar, select a topic. For example, Games -> Action Games. Page is navigated to https://www.reddit.com/t/action_games/
3. From the same page, navigate to https://www.wikipedia.org/ and then open it in a Taskbar Tabs window
4. In the Taskbar Tabs window, notice that the “Back” button is actionable
5. Click the “Back” button several times
6. Notice that from the Wikipedia page, users can go back to both Reddit pages and ultimately to the new tab page from where the whole process was started i.e. navigation history is preserved from before the Taskbar Tabs window was created

Actual results:
Navigation history is preserved for Taskbar Tabs windows when created.

Expected:
There should be no navigation history from before the Taskbar Tabs window was created, the page that was opened in said window being the first item in the navigation history of the Taskbar Tabs window.