The problem of causality at the quantum level has a simple solution:

At the quantum level, there's no clearly defined sequence of events, because the massless quanta and field disturbances that shape the quantum phenomena we observe experience any of our time intervals as instantaneous events. What we experience as processes are single events for the massless carriers involved.

This is because any phenomena we observe as propagating at the speed of light experiences, in fact, zero proper time. No time elapses for those quanta or disturbances.

So cause and effect seem to be happening at once at the quantum level because for each massless carrier, the interval we observed really takes place at once. At the speed of light, any evolution we infer is a single blink of existence with no time implications.

Cause and effect sequences only make sense to us, because they are one and the same thing for the massless quanta that shape the quantum phenomena we are considering.

The speed of light is the ultimate spacetime compression factor, as nothing can experience anything faster than instantly, regardless of what others could say about its speed.