On openSUSE Tumbleweed 20211005 (with shim 15.4-4.2 and Secure Boot enabled),
booting the newest Kernel:stable kernel 5.14.10-2.1.g2878fd1 leads to:

> Loading Linux kernel-default-5.14.10-2.g2878fd1-default ...
> error: ../../grub-core/kern/efi/sb.c:150:bad shim signature.
> Loading initial ramdisk ...
> error: ../../grub-core/loader/i386/efi/linux.c.98:you need to load the kernel first.
> 
> Press any key to continue..._

The previous Kernel:stable kernel 5.14.9-2.1.gd0ace7f did not have this issue.

The issue seems to be similar to the previous boo#1188142 (Kernel 5.13.1 does
not boot due to bad shim signature).