Can't login to Instagram using requests

You can use authentication version 0 - plain password, no encryption:

import re
import requests
from bs4 import BeautifulSoup

from datetime import datetime

link = 'https://www.instagram.com/accounts/login/'
login_url = 'https://www.instagram.com/accounts/login/ajax/'

time = int(datetime.now().timestamp())

payload = {
    'username': '<USERNAME HERE>',
    'enc_password': f'#PWD_INSTAGRAM_BROWSER:0:{time}:<PLAIN PASSWORD HERE>',  # <-- note the '0' - that means we want to use plain passwords
    'queryParams': {},
    'optIntoOneTap': 'false'
}

with requests.Session() as s:
    r = s.get(link)
    csrf = re.findall(r"csrf_token\":\"(.*?)\"",r.text)[0]
    r = s.post(login_url,data=payload,headers={
        "user-agent": "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.120 Safari/537.36",
        "x-requested-with": "XMLHttpRequest",
        "referer": "https://www.instagram.com/accounts/login/",
        "x-csrftoken":csrf
    })
    print(r.status_code)
    print(r.url)
    print(r.text)

Prints:

200
https://www.instagram.com/accounts/login/ajax/
{"authenticated": true, "user": true, "userId": "XXXXXXXX", "oneTapPrompt": true, "reactivated": true, "status": "ok"}

In order to do it, you need to do some investigation job on their javascript.

After a little research, I got that they use AES-GCM with 256 bits key length, they have some prefix of 100 bytes that I still do not know what is it, then they concatenate the password to it and encrypt the whole message 100 + len(password).

You can read about AES-GCM, get the key, iv, and additional data from their code, and complete the job yourself.

I hope that I have helped, Good Luck :)