1936285 - [Private Window] imdb.com influences navigating in a tab (back/forward) in which multiple websites were loaded

Status: NEW

(Core :: DOM: Navigation, defect)

Description

[Bogdan Maris, Desktop Test Engineering]

Attachment: Gif showing the issue

Found in

• Nightly 135.0a1

Affected versions

• Nightly 135.0a1

Tested platforms

• Affected platforms: Windows 10, macOS 12 and Ubuntu 22.04
• Unaffected platforms: none

Preconditions

• Have browser.navigation.requireUserInteraction pref set to true if not already set as default
• Run the test in a Private Window

Steps to reproduce

1. Open a Private Window
2. Navigate in the same tab on a few websites: https://www.mlb.com/tv/g632367?affiliateId=SCORES , https://imdb.com/ , https://support.microsoft.com/en-us/topic/windows-10-update-assistant-3550dfb2-a015-7765-12ea-fba2ac36fb3f , https://wikipedia.org
3. Use the back button to navigate until it reaches the first visited website
4. Use the forward button to navigate until it reaches the last visited website

Expected result

• Every website visited in a tab is revisited while using back/forward navigation buttons.

Actual result

• When reaching IMDB the flow is broken and all the visited website after IMDB are not accessible with back/forward button in the same tab anymore

Regression range

• Will look for a regression asap, not sure if this is something recent or not since only private browsing is affected.

Additional notes

• Not sure if this is something that the website itself is at fault and we can't do anything about it, like Twitter but since this is only reproducible in Private Windows means that maybe we can do something (or not). Though it looks like this is the exact same behavior we have when we activate Strict mode for Enhanced Tracking Protection in normal browsing.
• Marking the other versions of Fx unaffected since this feature is not turned on in earlier builds.

Comment 1

[Daniel Bodea [:danibodea]]

This issue is not a regression because:

1. The same behavior can be observed in builds as old as Nightly v95.0a1 from 2021-10-12.
2. Builds starting with Nightly v95.0a1 from 2021-10-11 and older show even worse behavior. When using the back button the first time in step 3, the New Tab page is shown so all the other 3 websites are no longer shown.

Further build investigation (in autoland) cannot be provided using Mozregression because the change is too old.

In conclusion, I will be removing the regression tag.