1897986 - The Tab Preview does not update after switching the browser theme

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[Patriciu Pop [:ppop], Ecosystem QA]

Attachment: tapPreview_change_theme.gif

[Affected versions]:

• Firefox Nightly 128.0a1 (Build #20240520214633)

[Affected Platforms]:

• Windows 10 x64
• macOS 13.6.2
• Ubuntu 22.04 x64

[Prerequisites]:

• Have the latest Firefox Nightly 128 installed.
• Have a browser profile enrolled in a Nimbus experiment that enabled the tabPreview feature.
• Have the browser's dark theme enabled.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Navigate to a website that changes based on the system theme. (e.g. x)
3. Change the browser's theme to light.
4. Refresh the website's page.
5. Open a new tab and mouse over the previous tab.
6. Observe the tab preview.

[Expected result]:

• The tab preview is displayed with the light theme version of the page.

[Actual result]:

• The tab preview is displayed with the original dark theme version of the page.

[Notes]:

• Attached a screen recording of the issue: