As you may be aware, Qt 6 arrived at the end of 2020 as the next-generation Qt application framework with new technologies and features for building more modern Qt software.
Now the KDE Project aims to adopt Qt 6 for their popular KDE Plasma desktop environment and apps. At the moment, all KDE apps and the KDE Plasma desktop environment rely on the current Qt 5 technologies, but the KDE Project wants to start migrating them to Qt 6 in an attempt to provide users with new functionality.