Comment 5 for bug 1919314

The message can not be shown only if the package is going to ask questions as debconf would need to extract the questions beforehand (and find none) for that to work – but it can't do that without apt-utils. :)

Not sure about the stderr vs. stdout, I guess the rational is that its more important than the "normal" output. In any case, this is something you will have to bring up with debconf… reassigning there (and resetting status).