Are questions about Ubuntu Virtual Machines on topic here? For example: https://superuser.com/questions/1105737/ubuntu-16-on-hyper-v-screen-flicker-and-other-problems. Yes I know that is a SuperUser question but would that be on-topic here?
As ever here, it really depends on what exactly is asked.
These type of questions would be on-topic when running Ubuntu in a VM with a different host
- Ubuntu in Virtualbox won't boot?
- I have error X when running Ubuntu in a VM
- Grub rescue, Ubuntu VB PLS HELP!!!!
These would be off topic when running Ubuntu in a VM with a different host
- Can't install VB in OSX to run Ubuntu
- Windows problem after installing Ubuntu in Virtualbox
When running Ubuntu as the host, it is sort of flipped, so on topic
- Can't install VB in Ubuntu
- Ubuntu problem after installing Windows in Virtualbox
- Windows in Virtualbox won't boot, Ubuntu host? I have error X when
- running OSX in a VM with Ubuntu host
- Win 10 recovery screen, in VB on Ubuntu PLS HELP!!!!
So in summery, it is about how much the question is about Ubuntu, OSX crashes in VB with Ubuntu host is off topic because it is an OSX issue but Ubuntu crashes in VB on OSX host is on topic because Ubuntu has the issue.
The question in your example would be on topic here, it is Ubuntu that has a problem, not the Win 10 it is running on.
I hope this helps clear up your confusion a bit.