m_m さん たかちゃん★ さん お知らせありがとうございます
https://www.mozilla.org/en-US/firefox/90.0/releasenotes/
Security Vulnerabilities fixed in Firefox 90 - Mozilla Foundation Security Advisory 2021-28
https://www.thunderbird.net/en-US/thunderbird/78.12.0/releasenotes/
Security Vulnerabilities fixed in Thunderbird 78.12 - Mozilla Foundation Security Advisory 2021-30