eh, I daily-drive a -fsanitize=address -fsanitize=undefined build of Qt and actual memory bugs are almost never a thing - I think the only time I had some were in tooling executables such as qmllint, but not in the framework itself. Most of the bugs by large are more "behaviour" bugs.
I’m impressed that QT runs clean enough under ubsan for daily use.
Here is another bug that led to crush thatt I reported while developing my block editor:
https://qt-project.atlassian.net/browse/QTBUG-124572