"Firefox does not trust this site because it uses a certificate that is not valid for magmalabs.io. The certificate is only valid for the following names: m.magmalabs.io, www.magmalabs.io
Chrome has a heuristic they call SSLCommonNameMismatchHandling: if Chrome tries to connect to a site like "https://example.com" but the returned cert is for the "www." subdomain of the same domain, Chrome will silently redirect to "https://www.example.com".