Inconsistent behaviour with .env-File between docker-compose v1 and docker compose v2

[wollomatic]

Description

Handling of strings in the .env-Files differs between Compose V1 and Compose V2.
In V2 some characters are interpreted while they are unchanged in V1.
I didn't find any mention of the difference in the documentation.

Steps to reproduce the issue:
.env:

456=ABC
TESTVAR1=123#456
TESTVAR2=123$456

compose.yaml:

---
services:
  busybox:
    environment:
      TESTVAR1: $TESTVAR1
      TESTVAR2: $TESTVAR2
    image: busybox

Describe the results you received:

$ docker-compose config (Compose v1)

services:
  busybox:
    environment:
      TESTVAR1: 123#456
      TESTVAR2: 123$$456
    image: busybox
...

$ docker compose config (Compose v2)

name: compose_bugreport
services:
  busybox:
    environment:
      TESTVAR1: "123"
      TESTVAR2: 123ABC
    image: busybox
...

Describe the results you expected:

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker compose version:

Docker Compose version v2.5.0

and docker-compose version:

docker-compose version 1.29.2, build 5becea4c
...

[blacksheep--]

I can confirm and this is not the only inconsistency between v1 and v2. See #9442 .

[ndeloof]

tested on latest release:

$ docker compose config
name: truc
services:
  busybox:
    environment:
      TESTVAR1: 123#456
      TESTVAR2: 123$$456

So, closing this one as "fixed"