If this is for openSUSE you probably want to share this with the openSUSE
folks at https://forums.opensuse.org/ as this particular forum is for SUSE
Linux Enterprise, and is meant to provide support about the Customer
Center. There is an applications forum for SLED which may be
more-appropriate if you are using SLED, and if so please provide
information about your version of the OS, Firefox version, and the
specific URL to test.

With my openSUSE setup, closing out tabs, windows, etc. when a window is
running has never been a problem, but it could be a new type of video
(HTML5?) that you are seeing which behaves differently, so duplication
would be important so those details will help with that process.

--
Good luck.

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