Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
@harrymc hard to tell, usually randomly, but my observations tell me it happens a) when I remote to the machines simultaneously or when I use Hyper-V "connect to machine", I tried to install the latest version of Parsec Virtual Display Driver, then one in one guest I can manually adjust the resolution to 4k but then after a bit of use and reboots, it's back to 1920 max.