COPY with --exclude does not apply to sub-directories (in general)

While I know, I can use .dockerignore for that, I wanted to try out COPY --exclude and found that

COPY --exclude .venv . .

Actually does not omit a/b/.venv. And neither does

COPY --exclude */.venv . .

But actually

COPY --exclude */*/.venv . .

does. So my question is: Is there a syntax to exclude .venv regardless to where it appears in the tree?

If not, I think, adding that detail might make the COPY documentation a little more insightful.

.dockerignore would not work differently either. Use two asterisks without a slash between them.

COPY --exclude **/.venv . .