For those of you running OpenSUSE Virtualbox 6.1.4 and have updated to 530.x versions.
No guest can be resized. the guest seem to run the latest version fine - the host not.
I have had to go back to 528.1 on the host to get resizeable virtual machine windows.
I have never gotten VMSVGA to resize - I have to go back to VBOXVGA to get resizeable windows.
If you need 528.1 for your host - I have them and can Firefox send them to you.
you just need to run this to get them installed and disable the Virtualization repo (or it will tell you there is a newer version)
zypper in -f virtualbox-6.1.4-lp151.528.1.x86_64.rpm virtualbox-kmp-default-6.1.4_k4.12.14_lp151.28.44-lp151.528.1.x86_64.rpm virtualbox-qt-6.1.4-lp151.528.1.x86_64.rpm
download with this link until 4/8
https://send.firefox.com/download/2cbf6197f8dcd6c9/#pjs7iIHpQdM8nvXhqiJJmw