The Qt Company has formed an open release of Qt 5.15.6, which includes fixes for the 5.15 LTS branch, the current updates for which are generated only for commercial license users (others are encouraged to use the Qt 6.x branch). For commercial users, the Qt 5.15.6 update was published a year ago. Some of the fixes available in this release have been brought to distributions in the form of a patch set maintained by the KDE project. The Qt 5.15 branch was published in May 2020 and will be maintained until May 2025. The next major release of Qt 6.4 is scheduled for September 29th.
Source: opennet.ru