QUOTE(Cairo94507 @ Oct 31 2022, 09:48 AM)
That had to be from someone sitting on top of the door. That should weld up nicely.
A crack typically will grow perpendicular to the axis of major stress. Looking at the shape of the part it is hard to imagine a force acting perpendicular to that crack from any body flex etc. especially since the mount bends 90 degrees towards the front of the car.
It doesn't look like the car was ever hit into that fender area based on the rust photos.
With someone sitting on the end and/or driving around with the door wide open that is the exact fracture you would expect to see. The moment arm would pivot on the bottom hinge with the top hinge resisting all the force as the the bolt is trying to shear at the holes. That is why the crack is larger at the top bolt. Likely that the bolts were not fully torqued or loose when it happened.
If the door is original to that damage it may have stretched the hole on the hinge and made it oval. Also check to see if the top bolt shown in the first photo is still perpendicular to the surface. If it angles outwards, there is a good chance that force down on an open door did the damage.