Using Docker YML file with context to parent (..) takes too long to build under WSL2

I have this folder structure

folder_ext
folder_docker
       |---> folder_int
folder_1
folder_2
.......

My docker files are all included inside the folder_docker. Inside my docker-compose.yml file, I set the context like this

version: '3'
services:
  nginx:
    container_name: my_nginx
    build:
      context: ..
      dockerfile: ./folder_docker/nginx/Dockerfile

Inside the Dockerfile I copy some files from folder_ext

COPY ./folder_ext /container_folder_ext

but somewhere below I copy also files from folder_docker/nginx/nginx.tmp

COPY ./folder_docker/nginx/nginx.tmpl /etc/nginx/conf.d/nginx.tmpl

I am using also .dockeringore to ignore folders & files that I am not using.

Unfortunately, this takes too long under WSL2 (Ubuntu distro) to begin the building process about ~25 minutes before it starts to process the 1st command inside the Dockerfile. I don’t know why, but that’s is a huge problem for me since I want to make many builds and I am losing my time with this stall.

If I use an alternative scenario like this below, where context is set inside the folder_ext,

version: ‘3’
services:
nginx:
container_name: my_nginx
build:
context: ../folder_ext
dockerfile: ../folder_docker/nginx/Dockerfile

the build begins almost instantly (~2 seconds) BUT I get an error "docker forbidden path outside the build context" for the 2nd COPY

COPY ../folder_docker/nginx/nginx.tmpl /etc/nginx/conf.d/nginx.tmpl

I don’t want to move my folder infrastructure just to make it build faster because it’s a git project that follows this folder structure. This seems to be a WSL2/Windows problem since under the production server the building times are acceptable.

Any other solution?

Source: Docker Questions