Generally people think that things coming down the line have more effect, as they change things earlier on.
It’s a faulty assumption.
Think about the difference between a solid and a fluid. Push a rod from upstream and the particles at the other of the rod move simultaneously and predictably. If a process is rigid, it works this way. Delay upstream equals the same delay downstream.
Now consider a calm, flowing stream, introducing an obstruction in the middle of it, a bridge pier for example, and all sorts of wild things happen both upstream and downstream. The fluid speeds up around the obstruction. Eddy’s form. There may be recirculation where some of the water starts to flow backwards. It’s unpredictable.
Most business processes are more like the fluid. When something goes wrong downstream, it doesn’t mean upstream isn’t seeing any effects. Everything is a system, address them as such.