Your backtrace had to do with Accessibility issues. Unfortunately Mac Accessibility and Qt Accessibility have not gotten all the bugs worked out in Qt.
Code:
Thread 0 Crashed:: Worker Dispatch queue: com.apple.main-thread
0 libobjc.A.dylib 0x1846c9820 objc_msgSend + 32
1 AppKit 0x188d140f0 NSAccessibilityPostNotificationForObservedElementW ithUserInfo + 132
2 QtWidgets 0x108a19798 QTableView::currentChanged(QModelIndex const&, QModelIndex const&) + 216
3 PyQt6.QtWidgets.so 0x1091cf7c8 sipQTableView::currentChanged(QModelIndex const&, QModelIndex const&) + 148
4 QtCore 0x105d207fc 0x105bec000 + 1263612
5 QtCore 0x105f30c24 QItemSelectionModel::setCurrentIndex(QModelIndex const&,
So my guess is your move to macOS 26, either reverted your MacOS Accessibility settings to turn them off or turned off other MacOS utility software that used Accessibility to function.