The Qt Company obviously don't think app developers using slightly old versions of their software provide any value to their shareholders, even though you're helping to grow the broader Qt ecosystem (libraries available, product awareness, knowledge sharing, growing the job market, etc).
As far as the Qt company are concerned if you're a FOSS app developer, and not on bleeding edge Qt 6 and actively contributing bug reports (i.e. acting as their outsourced QA), then you're just a worthless leech.
The feeling is the Qt library is only FOSS at this point because their hands are tied contractually by the KDE foundation.
This has lead the KDE foundation to create a surprisingly active fork of Qt 5.15:
https://invent.kde.org/qt/qt/qtbase/-/commits/kde/5.15
which is now the default Qt 5 base package on Arch Linux:
https://github.com/archlinux/svntogit-packages/blob/packages...