How to setup buildpack to push to Artifact registry?

[Fab-T]

Hello,
I have a CI running on GKE (with WLI+SA binded to role Artifact Registry Writer) that works perfectly when building/pushing images with Kaniko to google artifact registry.
I would like to move to buildpacks and I read that google buildpacks uses google cloud libraries that leverage ADC flow so it should directly publish like kaniko is doing.
Unfortunately, when I try the cnb/lifecycle/creator it fails at analyzer step with error authenticating to the registry and not having the read permission… but the KSA has the correct permission via WLI -> Artifact Registry Writer.

To validate: I build a custom google buildpack image with Google CLI and run a curl get command and it returns a response.
curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" "$MY_REGISTRY"

I even tried to create a docker config.json file but still facing the same error.
Could you please help me?
Thanks for your support
PS: Here is the CI build
build image:
stage: build
image:
name: $IMAGE_PACKBUILDER
before_script:
#create docker credentials via gcloud cli
- mkdir ~/.docker
- echo "{"auths":{"$GCP_REGISTRY":{"username":"gsa@my_project.iam.gserviceaccount.com","password":"$(gcloud auth print-access-token)"}}}" >> ~/.docker/config.json
script:
- /cnb/lifecycle/creator -app=. $BUILD_IMAGE:latest