To me, it still looks like a mystery.
At some time, we have all experienced an anomalous resynchronisation event. You have captured the data from one such event. I am not sure what conclusion can be deduced from that data.
I will agree that the shape of the dips, present in the QLN plot (from the anomalous resynchronisation event), look similar to the dip(s) that would be seen in an Hlog plot from a circuit which has the defect of a bridging tap. However it is wrong to make any conclusion that a bridging tap is present in the circuit from what can be seen in the QLN plot.
A QLN plot would give indications of possible RF ingress, the state of the overall AC balance of the pair, cross-talk from adjacent circuits, etc.
An Hlog plot would give indications of possible physical defects in the circuit, the presence of bridging tap(s), of oxidised high resistance or semi-conducting joints, the overall attenuation loss of the conductors, etc.