[IAmBroom]

All three bolts at critical level. A massive strain happens along. They pop: one, two, three!

It's not that unexpected.

[lazide]

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.