dist-upgrade fails on libc6 because "kernel too old"

This doesn't answer the question, but it explains why there's no answer.

Problem was that the "virtual host" in this case was a container, it didn't use the kernel that was shipped with the operating system, but on the server hosting the container. I was informed that I would have to upgrade the container through the hosting service, which would have come with additional cost. Ended up getting a true virtual server instead so I have more control.