I created an API on my local computer that is connected to GCP services and runs perfectly. However, when I deploy it on App Engine, I encounter an error whenever I use a POST method that includes a file. other method without involving file is somehow working fine.
in my logs it shows this error :

db=postgres,user=postgres FATAL: password authentication failed for user "postgres"

idk why… its running perfectly in my local, but not when deployed

is it related to app.yaml?

runtime: nodejs18
env: standard
instance_class: F1

env_variables:
  API_KEY: <MY_API_KEY>
  PORT: 5000
  CONNECTION_STRING: postgres://postgres:<my_password>@<instance_public_ip>:5432/<DB_NAME>
  FIREBASE_API_KEY: <FIREBASE_API>
  FIREBASE_AUTH_DOMAIN: <PROJECT_ID>.firebaseapp.com
  FIREBASE_PROJECT_ID: <PROJECT_ID>
  FIREBASE_STORAGE_BUCKET: <PROJECT_ID>.appspot.com
  FIREBASE_MESSAGING_SENDER_ID: <MESSAGE_SENDER_ID>
  FIREBASE_APP_ID: <FIREBASE APP ID>
  MEASUREMENT_ID: <MEASUREMENT_ID>
  PROJECT_ID: <PROJECT_ID>
  BUCKET_NAME: <MY_BUCKER_NAME>

handlers:
  - url: /.*
    script: auto

I’VE BEEN WORKING ON IT FOR DAYS. thank you.