I have a more technical question, It was my understanding that Android apps no longer trusted user added certificates by default starting Android 7 (https://and

I have a more technical question, It was my understanding that Android apps no longer trusted user added certificates by default starting Android 7 (https://android-developers.googleblog.com/2016/07/changes-to-trusted-certificate.html https://android-developers.googleblog.com/2016/07/changes-to...), but on the talk, they were able MITM Android 8.1, are they modifying the apps to trust their CA certs or is there something I am missing?