Keep route prefix when using route in App Platform

I have a spec app.yml that I use to setup a service and a frontend in the App platform (I trimmed down the yaml file):

name: airmeeple

static_sites:
- name: frontend
  source_dir: frontend
  routes:
  - path: /

services:
- name: backend
  source_dir: backend
  routes:
  - path: /api

When DO re-routes requests to the backend, it strips the prefix /api such that if the request service.com/api/user, the service will receive the request /user.

Is it possible to configure the reverse proxy such that the prefix is kept when rerouting the request, such that the service sees a request with the path /api/user?

Thanks in advance!