This is completely wrong. Causality never breaks down.

Massless quanta at the speed of light don't experience spacetime intervals. They describe null geodesics in 4D, and their proper time is zero. So we could say they feel they are leaving and arriving at the same time.

Then, what appears to be light speed for us means infinite speed for them, because they feel they are instantaneous. They traverse any distance in no time (for themselves) so they’re, effectively, teleporting instantly at infinite speed.

On the other hand, matter observers can’t reach instantaneity, as they are forced to move below c.

It’s true that each observer has its own subjective way of ordering events depending on speed (as they go detecting light signals in different orders and their proper times vary widely), but there’s no way any observer could detect a massless carrier before it’s really emitted.

Causality is always enforced. At the speed of light, it just happens that it “transforms” into instantaneity. As nothing can travel faster than light, causality never breaks down, no matter what any material observer could infer from its particular spacetime frame of reference.