Help needed - anormal build on supervised installation

Hi everyone, I’m looking for help in debugging an addon that builds in an unexpected way on an Home Assistant supervised setting.

More specifically : I have cloned the bitwarden community addon and added it in my repository. For me and several other users, my cloned addon works perfectly. However, for one user, it does not build normally.

System: Debian GNU/Linux 10 (buster) (armv7 / raspberrypi4)
Home Assistant Core: 2021.1.4
Home Assistant Supervisor: 2021.01.5

The dockerfile strategy is to get bitwarden files from the bitwarden image, copy it in a debian base image, then execute the bitwarden executable at boot : see dockerfile on github
His supervisor build log is normal : see here
His addon startup log however shows that even though the debian base image was installed, the bitwarden files are absent and does not execute : see here

It seems to me that the dockerfile doesn’t execute properly on his system, and doesn’t apply the COPY commands. Also, his docker layout (extracted from portainer) is very strange : see here. It looks like the bitwarden image but not at all like the dockerfile structure that I would have expected.

Would someone have pointers on what is the cause ? Thanks!