Shaded area either side of mean on line graph - matplotlib, seaborn - Python [duplicate]

Question

`def comparison_visuals(df_new):
matplotlib.rc_file_defaults()
ax1 = sns.set_style(style=None, rc=None )
fig, ax1 = plt.subplots(figsize=(12,6))
sns.lineplot(data = df_new, x='Date', y= 
(df_new['Transfer_fee'])/1000000, marker='o', sort = False, 
ax=ax1)
ax2 = ax1.twinx()
from matplotlib.ticker import FormatStrFormatter
ax1.xaxis.set_major_formatter(FormatStrFormatter('%.0f'))
sns.lineplot(data = df_new, x='Date', y='Inflation', alpha=0.5, 
ax=ax2)
from matplotlib.ticker import FormatStrFormatter
ax2.xaxis.set_major_formatter(FormatStrFormatter('%.0f'))
comparison_visuals(df_new)'

(Edited to paste code above)

Can anyone tell me what the shaded area represents on my line graph (see screenshot)? The middle line represents the mean. I haven't specifically added it. I would like to know first what it is and secondly how to remove it (I might chose to keep it if I find out what it represents and it adds value to my visualisation).

Any related answers I've come across don't del with this directly. Thansk in advance.

Screenshot of line graph