3 10mm bolts failing simultaneously after two decades (on direct it seems) is unexpected! If it were an installation problem, I can’t imagine it would take that long and that they’d all go at the same time. Ditto for corrosion… people take victory whips all the time.
It is absolutely unexpected in climbing. Even a single bolt failing is highly unusual.
Additionally, the rope length extends quite a bit of an anchor fails (and it partially recovers it’s elasticity before the other anchors engage). Later anchors would not get forces exceeding a normal ‘healthy’ bolts limits.
So there is some systemic failure involved in this scenario.
