Nature doesn't care if you know which way a particle went, what matters is the number of decoherence

Nature doesn't care if you know which way a particle went, what matters is the number of decoherence events in the path?

The reason you get fringes after the second decoherence event in the quantum eraser experiment is because, any quantum wave that is going to decohere will be a wave packet from the beginning. Wave packets use spacetime, so the second event causes that wave packet to go back to being unreal coherent waves that don't use spacetime.