Wouldn't say so. The who found the Vulnerability where at least talking to the people at chrome and firefox: Quote from there Blogpost (https://medium.com/bugb

Wouldn't say so. The who found the Vulnerability where at least talking to the people at chrome and firefox: Quote from there Blogpost (https://medium.com/bugbountywriteup/zoom-zero-day-4-million-webcams-maybe-an-rce-just-get-them-to-visit-your-website-ac75c83f4ef5 https://medium.com/bugbountywriteup/zoom-zero-day-4-million-...) "Apr 10, 2019 — Vulnerability disclosed to Chromium security team. Apr 19, 2019 — Vulnerability disclosed to Mozilla FireFox security team." So, not entirely unrealistic that the other Browser manufacturer also got a notice.