conditional formatings runs well on vs code bt background color not showing on existing excel file

Question

import pandas as pd

df = pd.read_excel('disk.xlsx')

def color(value):
    if value == 'File Uploaded!' :

        color = 'green'
    else:
        return
    return f'background-color: {color}'
    


df.style.applymap(color, subset=['file_status'])

df.to_excel('disk.xlsx',index=None)