html does not appear in jupyter

I use the following code

import folium
 import pandas as pd
 
 df = pd.read_csv('meteo.csv', encoding='cp1251', sep =';')
 customers = zip(df['lat'], df['lng'])
 m = folium.Map(location=[70, 100], zoom_start=1)
 folium.Marker(location=customers[0]).add_to(m)
 folium.Marker(location=customers[1]).add_to(m)
 folium.Marker(location=customers[3]).add_to(m)
 
 m

if markers are 2, then the folium displays a map with markers, but if markers are 3 or or more, then I see an empty window in jupyter, there are no errors. How to fix it?

The case is most likely in Jupiter.
If I run the code:

    def embed_map(m):
        from IPython.display import HTML
    
        m.save('index.html')
        with open('index.html') as f:
            html = f.read()
    
        iframe = '<iframe srcdoc="{srcdoc}" style="width: 100%; height: 750px; border: none"></iframe>'
        srcdoc = html.replace('"', '&quot;')
        return HTML(iframe.format(srcdoc=srcdoc))
    
    
    embed_map(m)

I get the correct html, but it also does not appear in jupyter.

Reproduce the supplied folium and pandas example in Jupyter Notebook, first with two markers and then with three or more. Compare the rendered notebook output with the generated index.html and the iframe returned by embed_map. Done means maps with three or more markers render correctly without an empty output or errors.