Control: severity -1 normal dkms never risks creating an unbootable environment by exiting with an error during the configuration of the corresponding linux-image-* package when a module fails to build. Even though it looks annoying when the failing dkms packages are not-so-critical to booting the system, dkms has no knowledge about which package is critical and which is less harmful.
I'm downgrading the issue to normal severity to allow more discussion on possible better handling of such cases in the future. For anbox-binder users who are reporting this issue to src:linux/src:dkms on sid/testing, please look for updating the source if it's very useful to you and hold the linux-image-* package for a while, or remove it to allow upgrading to newer version of linux packages for the moment. Regards, Aron