Twint doesn't return the number of tweets I am specifying

Question

Twint doesn't return the number of tweets I am specifying. Every time I run the code below I get different number which way below the limit specified in the code below

import twint
import pandas as pd 
import nest_asyncio
nest_asyncio.apply()

c = twint.Config() 
c.Username = "username"
c.Search = "search"
c.Since = "2021-07-25"
c.Until = "2022-03-02"
c.Limit = 500
c.Lang = "en"
c.Store_csv = True
c.Output = "file.csv"

twint.run.Search(c)