The KDE Patchset Collection has been rebased on top of Qt 5.15.6

[Antonio Rojas]

Beware that this update contains an ABI break in a public library:

https://code.qt.io/cgit/qt/qtbase.git/commit/src?id=4d6752e8d2ed9d303befe7adf7f6e4b6ba16bbb9

Even though they claim that this class is "not meant to be used externally", many applications do use the removed symbol and are broken after the update, including some KDE stuff:

freecad
kate
keepassxc
kstars
leocad
mediaelch
plasma-desktop (keyboard KCM)
qgis
sigil
texworks
tiled
ukui-control-center

I'd suggest to revert this commit in the patch collection.