Comment # 4 on bug 1207131 from Larry Rainey

You cannot install everything virtualbox on the host or the guest. By doing so
you have installed things that are not needed or tested. We don't install it
via gnome - we do test installs via yast and zypper - we test with Mate, xfce,
kde and gnome desktops.

I have no idea where your problem is coming from. I have 10 test machine with
different hosts desktops and every possible guest flavor (except OS/2) for
testing. Most of the problems are getting OBS to compile Oracles code. Oracle's
code compiles great outside OBS but OBS complains about many things Oracle does
and workarounds are devised to make it compile and work with OBS and openSUSE.
This has to be done to get openSUSE to sign the kernel modules.

Obviously, you have an unsigned kernel modules that did not get generated via
OBS because it is not signed.

This iswhat I would do to fix it on my machine:

zypper rm virtualbox*

To clean up the installed versions and just install the pieces need for a guest
or host.

so on a guest:

zypper in virtualbox-kmp-default virtualbox-guest-tools

on a host:

zypper in virtualbox virtualbox-kmp-default virtualbox-qt

when installed it should look like this:

on a guest:
zypper se -si virtualbox
Loading repository data...
Reading installed packages...

S  | Name                   | Type    | Version                                
 | Arch   | Repository
---+------------------------+---------+------------------------------------------+--------+--------------------------
i+ | virtualbox-guest-tools | package | 7.0.4-lp154.2.23.1                     
 | x86_64 | openSUSE-Leap-15.4-Update
i  | virtualbox-kmp-default | package |
7.0.4_k5.14.21_150400.24.38-lp154.2.23.1 | x86_64 | openSUSE-Leap-15.4-Update

On a host:
zypper se -si virtualbox
Loading repository data...
Reading installed packages...

S  | Name                   | Type    | Version                                
 | Arch   | Repository
---+------------------------+---------+------------------------------------------+--------+--------------------------
i+ | virtualbox             | package | 7.0.4-lp154.2.23.1                     
 | x86_64 | openSUSE-Leap-15.4-Update
i+ | virtualbox-kmp-default | package |
7.0.4_k5.14.21_150400.24.38-lp154.2.23.1 | x86_64 | openSUSE-Leap-15.4-Update
i+ | virtualbox-qt          | package | 7.0.4-lp154.2.23.1                     
 | x86_64 | openSUSE-Leap-15.4-Update