Write a single line insight for an ecommerce store from the following json that is an output of anomaly from visitor data:

json_data = {
'freq': 'weekly',
'placeholders_val': {'event_name': 'page_viewed', 'utm_source': 'facebook'},
'expr': "SELECT COUNT(DISTINCT visitor_id) as val FROM pf.m_ev_cust_view WHERE event_name = 'page_viewed' AND utm_source = 'facebook'",
'val_int': 1351.0,
'pct_chg': 253.66492146596858,
'is_anomaly': -1
}