You're probably running into a known bug (
#21774), that has already been fixed for the next release update. If you provide two virtual screens and the second one is turned off, both virtual screens get turned off. Either configure the VM to only provide one virtual screen, or turn on the second virtual screen from the VM window's menu.
After you've solved this issue, update the VirtualBox Guest Additions (in the guest) to 7.0.10.
The
VBox.log file shows that you have the VirtualBox Extension Pack 7.0.10 installed now, so the current contents of
/usr/lib/virtualbox/ExtensionPacks are probably no surprise now.
Edit:
Added the link to the Bugtracker ticket.