Dear Maintainer,

It's the same bug as 11 Oct 2021, and fixed with same solution (from Damir R.
Islamov) on 19 Oct 2021:

The issue is caused by mistakes in lines 16-17 of /etc/kernel/prerm.d/dkms
script
(quotes are misplaced).
The patch:
===========================================
-   name=`echo "$line" | awk '{print $1}' | sed 's/,$//'` | cut -d'/' -f1
-   vers=`echo "$line" | awk '{print $1}' | sed 's/,$//'` | cut -d'/' -f2
+   name=`echo "$line" | awk '{print $1}' | sed 's/,$//' | cut -d'/' -f1`
+   vers=`echo "$line" | awk '{print $1}' | sed 's/,$//' | cut -d'/' -f2`
===========================================

Regards

fyi: I'm force merging duplicate reports to #996104. The bug was fixed
upstream in 2.8.8, but Debian upgraded to 3.0.3 in the meantime
(bullseye never had this bug, because it only has version 2.8.4).

I assume folks tracking testing are going to have to manually downgrade
to 2.8.4, or upgrade to 3.0.3, because I think it's unlikely that there
will be a 2.8.8 release just for testing.

Bug 1006431 may have been fixed at the same time as bug 996104,
but this was not the same bug: bug 996104 was typos in the
/etc/kernel/prerm.d/dkms script, so that the

  dkms remove -m $name -v $vers -k $inst_kern -a $arch

command failed due to incorrect arguments. So what I did was to
run the correct command manually. This had the effect to remove
the installed module, but was still leaving some files there.

Or perhaps this command is expected to be run while the kernel
is still installed (it is normally run as a prerm.d script,
while I ran it after the kernel was removed).