1954516 - YouTube stops sending HDR video on Macbook when external Dell monitor is attached but not on Safari

Status: NEW

(Core :: Graphics, defect)

Description

[Kagami Rosylight [:saschanaz] (they/them)]

0. Detach all external monitors on your MacBook (Air M1 2020 in my case, macOS 15.3.2, Firefox Nightly 2025-03-13 / Firefox 136.0.1)
1. Open https://youtu.be/72A2Rf-V6oE
2. See it gives HDR video
3. Attach an external monitor (Dell U2723QE in my case)
4. Refresh the page (but let it be on the macbook monitor, not on the external monitor)
5. See it still gives HDR video
6. See whether Safari gets HDR video

Expected: Safari and Firefox should get HDR video
Actual: Only Safari gets HDR video

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:bhood, could you have a look please?

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