nginx-ingress 403 when accessing gRPC api running on http:*:80 without TLS

I'm trying to access a gRPC api running begind nginx-ingress. gRPC is running on port 80 without TLS. Here is my ingress configuration:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ${AUTH_API_IMAGE}-ingress
  annotations:  
    nginx.ingress.kubernetes.io/backend-protocol: "GRPC"
    nginx.ingress.kubernetes.io/grpc-backend: 'true'
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
    kubernetes.io/ingress.class: nginx
    cert-manager.io/cluster-issuer: letsencrypt
spec:
  ingressClassName: nginx
  tls:
  - hosts:
    - ${AUTH_API_HOST_NAME}
    secretName: ${AUTH_API_IMAGE}-tls-secret
  rules:
  - host: ${AUTH_API_HOST_NAME}
    http:
      paths: 
      - path: /
        pathType: ImplementationSpecific
        backend:
          service:
            name: ${AUTH_API_IMAGE}
            port:
              number: 80

Anyone has any idea what the issue can be ?