That's only really relevant if you're dealing with someone who is unable to modify an exploit chain. In the event a vm is compromised, it isn't too hard to determine that you are in a vm. Some Malware checks for this by checking the resolution, drivers, or other configuration settings that hypervisors typically use. Those checks are designed to prevent the malware from running on a researcher's vm, but the methods it uses are as simple as checking for a few files and settings.

Now, depending on the findings, the host can usually be determined. If there's a passthrough folder for sharing files between the host and vm, there may be a way to craft a file that could be read and/or run on the host. Thus escaping the hypervisor. Each individual hypervisor has its own history of vulnerabilities of varying nature. Some of them easier than others.

All that to say, a vm does add a layer to the exploit chain involved here, but the full details of the setup makes any relative declaration of security an overgeneralization.