Indeed. As someone somewhat familiar with "underhanded code" contests (not as a participant) and publicly known espionage norms. I'm unsure why people expect backdoors to have massive MOTD banners and not be reintroduced OpenSSL vulns from 2006 that "accidentally" got into the build process for certain releases of firmware 11 years later (this happened with the UK Huawei audit iirc). I'm also unsure why people expect specific examples of known backdoors when that in itself hurts counter espionage efforts.