Docker build - COPY/ADD/RUN --mount=type=bind does not preserve original UID/GID

I would like to copy all files from a folder in my docker build context.
The files (and folders) inside the folder are mixed with different owners and groups (e.g. UID=400 GUID=800 etc.), which I need to preserve (I also need to preserve timestamps, etc.)

So basically I need a 1:1 copy of the files to my docker image.

When I use ADD/COPY, it doesn't preserve the UID:GID which is also stated in the documentation.
(UID:GID 0 is standard - why?)

I have made a workaround which uses rsync (-a) with localhost, but it's not an ideal solution.
I could also use the docker cp command and commit the image but I would like to use this in my dockerfile.

I am using DOCKER_BUILDKIT=1

https://stackoverflow.com/questions/74546557/docker-build-copy-add-preserve-owner-group-permissions

There is clearly a bug in the COPY --chown parameter
I can use any username/groupname which is not present in /etc/passwd and/or /etc/groups - it always defaults to GID:UID=0

The COPY command should fail
https://docs.docker.com/engine/reference/builder/#:~:text=If%20the%20container%20root%20filesystem%20does%20not%20contain%20either%20/etc/passwd%20or%20/etc/group%20files%20and%20either%20user%20or%20group%20names%20are%20used%20in%20the%20--chown%20flag%2C%20the%20build%20will%20fail%20on%20the%20COPY%20operation.%20Using%20numeric%20IDs%20requires%20no%20lookup%20and%20does%20not%20depend%20on%20container%20root%20filesystem%20content.

Also:

RUN --mount=type=bind should act just as a -v parameter and keep the all the UID/GIDs?

No repository file or test is identified in the issue. Start by reproducing the behavior with a Dockerfile using COPY/ADD --chown and RUN --mount=type=bind under DOCKER_BUILDKIT=1, then trace the relevant BuildKit build entry points. Done means ownership handling matches the documented behavior, including failure for unresolved names and preservation where requested, with regression coverage.