The only thing that matters license wise for 99% of people is https://github.com/qt/qtbase/blob/dev/LICENSE.LGPLv3 which cannot be changed without renegotiating with KDE.
For reference, on arch linux, there is a grand total of 3 packages with a hard dependency on qt charts, one of those being a python binding to it. versus the whole of KDE plus a ton of other things that have no problem depending on "just" the LGPL parts of Qt.