In this code, which inserts data into a QStandardItemModel (called resourcesModel) with QTableView:

item = QStandardItem()
item.setData(123123, Qt.EditRole)
resourcesModel.setItem(1, 1, item)

double-clicking on a cell presents a default QLineEdit (which you can put letters into), instead of QSpinBox, which would be expected since data is an integer.

Possible explanation (by user eyllanesc on StackOverflow):

What happens is that PySide2 converts the integer from python to LongLong (QVariant::LongLong=4) in C++ which is not handled by the default QItemEditorFactory by default making a QLineEdit used (in PyQt is converted to QMetaType::Int=2).