not sure a social collapse is something that can be identified in real time, but rather a point identified by historical analysis at a later date to say, "this was the point of no return for the hegemonic order and its property relations" and it may be something like a persistent government shutdown that sees many programs never recover administratively/fall into corruption, a court ruling, a moment of political violence, etc. basically the single moment in a chain of events undermining the social order beyond which recovery is impossible.

this is an instructive read: https://gen.medium.com/i-lived-through-collapse-america-is-already-there-ba1e4b54c5fc