When I am sending a base64 string encoded file to azure functions for http trigger, it is sending a 413 error.

When I am sending a base64 string encoded file to azure functions for http trigger, it is sending a 413 error. {"statusCode":413,"message":"request entity too large"}. The base64Source: size.txt

My code:

import azure.functions as func
from azure.ai.documentintelligence import DocumentIntelligenceClient
from azure.core.credentials import AzureKeyCredential
from azure.ai.documentintelligence.models import AnalyzeResult
import logging, base64, imghdr

app = func.FunctionApp(http_auth_level=func.AuthLevel.FUNCTION)
    
@app.route(route="http_dataretrieval")
def http_dataretrieval(req: func.HttpRequest) -> func.HttpResponse:
    logging.info('Python HTTP trigger function processed a request.')
    endpoint = "" #blocked
    credential = AzureKeyCredential("")#blocked

    base64source = bytes(eval(req.get_body().decode()).get("base64Source"), encoding='utf-8')
    yo = base64.b64decode(base64source)

    extension = "." + imghdr.what(None, h=yo)

    with open("file" + extension, "wb") as f:
        f.write(yo)

    with open("file" + extension, "rb") as f:
        document_intelligence_client = DocumentIntelligenceClient(endpoint, credential)
        
        poller = document_intelligence_client.begin_analyze_document(
            "prebuilt-invoice", analyze_request=f, content_type="application/octet-stream"
        )

        result: AnalyzeResult = poller.result()

        invoice = result.documents[0]

        processed_dict = dict()

        for key, value in invoice.fields.items():
            if key == "Items":
                items = invoice.fields.get("Items")
                processed_dict["Items"] = dict()
                for id, item in enumerate(items.get("valueArray")):
                        processed_dict["Items"][f"{id + 1}"] = dict()
                        item_description = item.get("valueObject").get("Description")
                        if item_description:
                            processed_dict["Items"][f"{id + 1}"]["Description"] = item_description.get("content")
                        item_quantity = item.get("valueObject").get("Quantity")
                        if item_quantity:
                            processed_dict["Items"][f"{id + 1}"]["Quantity"] = item_quantity.get("content")
                        unit = item.get("valueObject").get("Unit")
                        if unit:
                            processed_dict["Items"][f"{id + 1}"]["Unit"] = unit.get("content")
                        unit_price = item.get("valueObject").get("UnitPrice")
                        if unit_price:
                            unit_price_code = (
                                unit_price.get("valueCurrency").get("currencyCode")
                                if unit_price.get("valueCurrency").get("currencyCode") else ""
                            )
                            processed_dict["Items"][f"{id + 1}"]["UnitPrice"] = {'Value': unit_price.get("contnet"), 'CurrencyCode': unit_price_code}
                            
                        product_code = item.get("valueObject").get("ProductCode")
                        if product_code:
                            processed_dict["Items"][f"{id + 1}"]["ProductCode"] = product_code.get("content")
                        item_date = item.get("valueObject").get("Date")
                        if item_date:
                            processed_dict["Items"][f"{id + 1}"]["ItemDate"] = item_date.get("content")
                        tax = item.get("valueObject").get("Tax")
                        if tax:
                            processed_dict["Items"][f"{id + 1}"]["Tax"] = tax.get("content")
                        amount = item.get("valueObject").get("Amount")
                        if amount:
                            processed_dict["Items"][f"{id + 1}"]["Amount"] = amount.get("content")
                continue
            processed_dict[key] = value.get("content", "lol")

        

        return func.HttpResponse(f"{processed_dict}", status_code=200)