I do get the warning using the same Firefox version on Windows. Note that the link in the article is mangled. The link text is <https://no-sct.badssl.com/ htt

I do get the warning using the same Firefox version on Windows. Note that the link in the article is mangled. The link text is <https://no-sct.badssl.com/ https://no-sct.badssl.com/>, but the actual href points to <https://certificate.transparency.dev/useragents/ https://certificate.transparency.dev/useragents/>. Your comment has the correct link which gives the warning.