This explains a new problem
On updated 43.x 15.0 and 15.1 to 15.2 to 15.3 when the new kernel came in the virtualbox guest no longer can be seen.
Every machine that was like that - I had to boot to run level 3 and zypper in kernel-default-optional kernel-default-extra as they did not get updated via zypper up

the machines that were virgin 15.2 got the 2 updates. this might be a bug?

On Tue, Jun 15, 2021 at 8:37 AM Martin Wilck <martin.wilck@suse.com> wrote:
On Di, 2021-06-15 at 08:27 -0500, Larry Len Rainey wrote:
> I have had to lock these because they cause issues:
>   kernel-preempt virtualbox-kmp-preempt
>  
> Are these really needed and can they be uninstalled and or locked?
>  kernel-default-extra-5.3.18-59.5.2
>   kernel-default-optional-5.3.18-59.5.2

This is caused by "closing the Leap gap". As the same binary packages
are shipped for SLE and Leap, but SUSE can't offer full enterprise-
level support for the entire universe of Leap modules, the kernel
package had to be split in parts.

 kernel-default: kernel + supported modules in SLES (SUSE Linux
Enterprise Server)
 kernel-default-extra: additional modules for SLED (SUSE Linux
Enterprise Desktop) or SLE-WE (Workstation extension)
 kernel-default-optional: additional modules that are neither in SLES
or SLED, but in Leap.

To bring your system to the full functionality your kernel-default
package had in Leap 15.2, you'll have to install both -extra and 
-optional.

OTOH, if you have standard hardware and no fancy other requirements,
you may not actually *need* either of them. They have "Supplements"
dependencies to the kernel-default package; thus they'll be installed
unless you use --no-recommends.

Regards
Martin