sys-fs/vdo-kmod-8.2.0.21 fails to build: /usr/src/linux-6.6.13-gentoo/Makefile:768: arch/amd64/Makefile: No such file or directory

[kripton]

I tried compiling sys-fs/vdo-kmod-8.2.0.21 against my running kernel. Sources are present, fully configured and compiled.
This is on an x86_64 machine and I am not cross-compiling the kernel.
Error message / build log:

>>> Running pre-merge checks for sys-fs/vdo-kmod-8.2.0.21
 * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Found sources for kernel version:
 *     6.6.13-gentoo
 * Checking for suitable kernel configuration options ...                                                                                                                                                                                                   [ ok ]

>>> Emerging (1 of 1) sys-fs/vdo-kmod-8.2.0.21::inode64-overlay
 * vdo-kmod-8.2.0.21.tar.gz BLAKE2B SHA512 size ;-) ...                                                                                                                                                                                                     [ ok ]
 * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Found sources for kernel version:
 *     6.6.13-gentoo
 * Checking for suitable kernel configuration options ...                                                                                                                                                                                                   [ ok ]
>>> Unpacking source...
>>> Unpacking vdo-kmod-8.2.0.21.tar.gz to /var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work
>>> Source unpacked in /var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work
>>> Preparing source in /var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work/kvdo-8.2.0.21 ...
>>> Source prepared.
>>> Configuring source in /var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work/kvdo-8.2.0.21 ...
>>> Source configured.
>>> Compiling source in /var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work/kvdo-8.2.0.21 ...
make -j4 -C /usr/src/linux M=/var/tmp/portage/sys-fs/vdo-kmod-8.2.0.21/work/kvdo-8.2.0.21 
make: Entering directory '/usr/src/linux-6.6.13-gentoo'
/usr/src/linux-6.6.13-gentoo/Makefile:768: arch/amd64/Makefile: No such file or directory
make[1]: *** No rule to make target 'arch/amd64/Makefile'.  Stop.
make: *** [Makefile:234: __sub-make] Error 2
make: Leaving directory '/usr/src/linux-6.6.13-gentoo'
 * ERROR: sys-fs/vdo-kmod-8.2.0.21::inode64-overlay failed (compile phase):

[inode64]

Ugh, I haven't looked at this ebuild in a while.
I started the creation but I didn't finish, now I'm a little busy.