arm64 images on Docker hub contain only x86_64 binaries

When trying to use the latest cincproject/cinc arm64 Docker images from the Docker hub, I get errors. Here is an example from a kitchen/dokken setup :

failed to open elf at /lib64/ld-inux-x86-64.so.2

After some digging, it seems the problematic file is /opt/cinc/embedded/bin/ruby, which is a x86_64 binary file (in an arm64 image).

I also went through the docker hub, and the latest (at the time of writing) image has an x86_64 layer inside : https://hub.docker.com/layers/cincproject/cinc/18.8.11/images/sha256-35004fda6d5e23aff9f12666bd866ad44044859e08be2b5a7c0c64df2d42b53c . The ARCH arg is set to x86_64.

I looked at previous images, and the latest non-problematic is 18.6.2 : https://hub.docker.com/layers/cincproject/cinc/18.6.2/images/sha256-6b0adbf1bc8feb60e495ff6ec275fba1c8c307d5623a8eda28538d46e79d555e