Note that erasing kernel-default-optional-5.14.21-150400.24.33.2 worked but erasing kernel-default-optional-5.14.21-150400.22.1.x86_64 does not. This is because the update kernel has the run_if_exists, whereas the GA kernel does not. So it'd be sufficient to uninstall the GA kernel first before doing the zypper dup.