Python - flask app doesn't serve images used in react app

I have a react project that is hosted in flask app.

This is the project folders:

/simzol/
└── backend/
    ├── app.py
    └── build/
        ├── index.html
        ├── images/
        ├── static/
        │   ├── css/
        │   └── js/
        └── other_files...

PS. the build folder is generated by react using the command "yarn build"

here's the flask app initializer:

app = Flask(__name__, static_url_path="/static", static_folder="build/static", template_folder="build")

that's how I serve the main route and any other path that isn't an API path (which should be handled by the react app. If the page doesn't exist, react should return the appropriate 404 not found page that I wrote):

@app.route("/") 
@app.route('/<path:path>')
def home(path=None):
    try:
        return render_template("index.html"), 200
    except Exception as e:
        return handle_exception(e)

When I run the app and go to the main route, I can't see my images load up.

What I tried:

1. move the images folder into the static folder. didn't change anything
2. change the static_url_path to empty string ("") and the static_folder to "build". That solves the problem but I encounter another problem when I surf any page that is not the root page (like /contactus) directly through the browser's url input field, I get 404 error from flask (not react)
3. I use relative image path in react src attributes, maybe changing that could fix the problem but if that solution works, I don't like it, because that makes the developing in react more complicated

I wanted the images to load up in both flask app in production and in react app (using npm start) for development. At the same time, I wanted unknown pages to be handled by react.
The most convenient solution I found is to put all the images under public/static/images instead of public/images and to change the src paths accordingly.
Then I can run yarn build and get the result build folder to the flask app folder (backend). That worked perfectly.