I was about to submit an update of kernel-default-base, but when comparing the
kmod provides I noticed that the Tumbleweed version was missing quite a lot of
them, like sha256_generic or zstd_{,de}compress.ko on aarch64.

I guess this is caused by

[  173s] Builtin modules for
/home/abuild/rpmbuild/BUILDROOT/kernel-default-base-5.9.11-1.1.g91426ef.55.1.x86_64/boot/vmlinux-5.9.11-1.g91426ef-default.xz
not available in
/home/abuild/rpmbuild/BUILDROOT/kernel-default-base-5.9.11-1.1.g91426ef.55.1.x86_64/lib/modules/5.9.11-1.g91426ef-default.xz/modules.builtin

The .xz seems wrong there, maybe that needs to be handled in
https://github.com/openSUSE/rpm-config-SUSE/blob/dc40e5779d59d088658ee3dfe1d1f732a9dca50f/scripts/find-provides.ksyms#L29
as well?