Question about lr_find()

When i run lr_find(), the lr show weird cure.
Why it is like this

plt.figure(figsize=(24,12))
for wd in [None, 1e-3, 1e-4, 1e-5]:
learn.lr_find(wds=wd)
learn.sched.plot()

plt.axvline(x=0.2, color=‘r’)