All my browsers are connected , even through different devices

I am using flask to develop a website and have used login_manager to deal with sessions.

When testing locally, I can log in to different accounts at the same time (one on chrome and one on microsoft edge).

However, after deploying my website on pythonAnywhere, when I log into one account on one browser, all browsers get logged in too. I have tested this on icognito, different ip, different devices, etc.

Does anyone know how to fix this?

login_manager = LoginManager()
login_manager.login_view = "login"

def load_user(user_id):
    return User.query.get(int(user_id))

this is my

from flask import Flask, flash
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
import os

app = Flask(__name__)
db = SQLAlchemy(app)

migrate = Migrate(app, db)

from app import views, models


app.config['SECRET_KEY'] = 'your_secret_key_here'

[formatted by admin]

How does the login view look like?