I am trying to populate form fields via selenium in python:
from selenium import webdriver
from selenium.webdriver.common.action_chains import ActionChains
The problem is that there are two other input elements with placeholder="Логин" and placeholder="Пароль" which are invisible. Make your CSS selectors specific to the login form:
login = driver.find_element_by_css_selector('form#loginForm input[placeholder="Логин"]')
pwd = driver.find_element_by_css_selector('form#loginForm input[placeholder="Пароль"')