slight screen corruption when maximizing window

Host: Ubuntu disco
qemu-kvm: 1:3.1+dfsg-2ubuntu2
libvirt: 5.0.0-1ubuntu2


Guest: ubuntu bionic
guest is using cirrus video, with the extra modules kernel package installed and the cirrus kernel module loaded

A non-maximized terminal window works just fine. As an example, I run "lsmod". It fills the screen, which then scrolls a bit.

The moment I maximize that window, though, the rendering breaks. I can see the commands I type, but not their output. See attached video.