This change will only affect you if you use Signal as your default SMS app on Android. Meaning that you use Signal on Android to receive and send both Signal and SMS messages from within the Signal interface.
If you do use Signal as your default SMS app on Android, you will need to select a new default SMS app on your phone. If you want to keep them, you’ll also need to export your SMS messages from Signal into that new app.
Today we are happy to announce the first step in advancing quantum resistance for the Signal Protocol: an upgrade to the X3DH specification which we are calling PQXDH. With this upgrade, we are adding a layer of protection against the threat of a quantum computer being built in the future that is powerful enough to break current encryption standards.