I have an issue with a stripe webhook, which I am running locally for the test.

async def my_webhook_view(request: Request, db: Session = Depends(get_db)):
    payload = await request.body()
    sig_header = request.headers.get('stripe-signature')
    event = None
    try:
        event = stripe.Webhook.construct_event(
            payload, sig_header, ENDPOINT_SECRET
        )
    except ValueError as e:
        # Invalid payload
        raise HTTPException(status_code=400, detail="Invalid payload")
    except stripe.error.SignatureVerificationError as e:
        # Invalid signature
        raise HTTPException(status_code=400, detail="Invalid signature")

    if event['type'] == 'checkout.session.completed':
        #email = event['data']['object']['customer_details']['email']
        # Check if the event has already been processed
        event_id = event['id']
        if db.query(ProcessedEvent).filter_by(id=event_id).first():
            return {"message": "Event already processed"}

        # Process the event
        session = event['data']['object']
        db_event = ProcessedEvent(id=event_id)
        db.add(db_event)
        db.commit()
        msg = fulfill_checkout(event['data']['object']['id'])
        if msg == "Event received":
            print("Event received")
            return JSONResponse(status_code=200, content={"message": "Success"})
        else:
            print("Event unprocessed")
            return JSONResponse(status_code=200, content={"message": "Cancel"})

There is no delay (1s), the event is immediately received, and the debugger enters well into return JSONResponse(status_code=200, content={“message”: “Success”})
but nothing happens on the stripe payment page.
I get a timeout after some time with the success url but everything has been correctly processed in the background tasks.

The checkout properly sets the success and cancel urls.

#Stripe Payment
@app.post('/create-checkout-session')
async def create_checkout_session(price_id: str = Form(...)):
    try:
        checkout_session = stripe.checkout.Session.create(
            line_items=[
                {
                    # Provide the exact Price ID (for example, pr_1234) of the product you want to sell
                    'price': price_id,
                    'quantity': 1,
                },
            ],
            mode='payment',
            success_url= f'{DOMAIN}/success',
            cancel_url= f'{DOMAIN}/cancel',
            billing_address_collection = 'required'
        )
    except Exception as e:
        raise HTTPException(status_code=400, detail=str(e))
    
    return RedirectResponse(checkout_session.url,303)