Almost all of the QMatrix element getters are implemented with __call__ and correctly type hinted.

QMatrix4x4 is implemented with __getitem__ and is not documented in the type hints.

I would expect this to be consistently implemented for all QMatrix classes.

from PySide6.QtGui import QMatrix3x3, QMatrix4x4

m33 = QMatrix3x3()
e11 = m33(0, 0)

m44 = QMatrix4x4()
e11 = m44(0, 0) # TypeError: 'PySide6.QtGui.QMatrix4x4' object is not callable
e11 = m44[0, 0] # This is not documented in the type hints

Either the following type hint needs to be added to QMatrix4x4 to document the real behaviour.

def __getitem__(self, item: tuple[int, int]) -> float: ... 

Or __call__ should be implemented on QMatrix4x4 to match the other QMatrix classes and C++.

Personally I would prefer the latter for consistency.

__getitem__ should be kept but undocumented for backwards compatibilty.