This is not a problem with linux-firmware itself, it does is trigger a rebuild of the initrd for all installed kernels but it's initramfs-tools which does this. It will try to generate an initrd for all kernels with a file in /var/lib/initramfs-tools, so it sounds like you have a file there for that kernel but no corresponding directory for that kernel in /lib/modules.
Changing this bug report to be against initramfs-tools.
This is not a problem with linux-firmware itself, it does is trigger a rebuild of the initrd for all installed kernels but it's initramfs-tools which does this. It will try to generate an initrd for all kernels with a file in /var/lib/ initramfs- tools, so it sounds like you have a file there for that kernel but no corresponding directory for that kernel in /lib/modules.
Changing this bug report to be against initramfs-tools.