Help interpreting model

Hi,
Can someone please help me interpret this graph from lr_finder()

screenshot-colab.research.google.com-2020.06.19-12_06_15

what might the flat part represent? Thanks !

The following chapter of fastbook covers the learning rate finder and how to interpret the graphs:

https://github.com/fastai/fastbook/blob/master/05_pet_breeds.ipynb (section improving our model).

Florian