Tumbleweed server with VirtualBox 6.1.36 installed.

Testing with many guests: Arch Linux, debian, fedora (stable and rawhide),
FreeBSD, Linux Mint, openSUSE LEAP 15.4, openSUSE Tumbleweed.

If a USB device (usually a flash drive) is attached when the guest is shutdown
or rebooted, the guest ends with an "Aborted" status.

This is new with 6.1.36 of VirtualBox from the opensuse Tumbleweed repository.

This problem is a nuisance with shutdown but precludes a successful reboot
requiring user attention.

This issue is not observed when openSUSE LEAP 15.4 is the host.

There are no useful messages in the log(s).

If the user remembers to detach the USB device before rebooting, the problem
can be avoided.  Yeah, like that's going to happen.