By confusing the browser, the fullscreen notification could have been delayed or suppressed, resulting in potential user confusion or spoofing attacks. This vulnerability affects Firefox < 108.
https://bugzilla.mozilla.org/show_bug.cgi?id=1795139
https://lists.debian.org/debian-lts-announce/2023/01/msg00015.html
https://lists.debian.org/debian-lts-announce/2023/02/msg00018.html
https://security.gentoo.org/glsa/202305-06
https://security.gentoo.org/glsa/202305-13
https://www.debian.org/security/2023/dsa-5322