This graph is also very interesting. The upper panel shows the oscillation of the local slopes. We are taking the different with the global value 5.7.

You can see clearly the oscillations are equally distributed above and below 0.
The panel below extracts the log periodic oscillations of n and show the main harmonic being dominant up to they year 2020, when the interference from other harmonics becomes large and the dominant frequency is lost in these higher frequencies.
This is what created confusion in interpreting the quasi-4 years peaks in the last cycles.