After a recent update to the 5.11 kernel, I noticed that the bcmwl-kernel-source wireless driver stopped working. Attempting to reinstall, I noticed the following message during the dkms build:

ERROR (dkms apport): kernel package linux-headers-5.11.0-7612-generic is not supported

This also caused the system76-dkms and system76-io-dkms packages to discontinue working on my system.

I ended up tracking this down to a missing /usr/src/linux-headers-5.11.0-7612-generic/include/generated/autoconf.h file. I tried manually reinstalling linux-headers-5.11.0-7612-generic, which includes the file, but for some reason autoconf.h refuses to install to the destination folder. I had to manually extract it from the .deb and copy it to the destination, after which the dkms modules all build and appear to function correctly.

I suspect this a deb packaging issue, but it's not clear to me how this file is being excluded from installation. I've seen a number of somewhat similar bug reports for broken drivers/firmware that may be linked to this.