There are a couple of other posts sniffing around this or similar issues, but they're mostly reviving years-old threads. Also, in my case, the behavior doesn't occur with Windows 10 or Linux guests. The problem: In Big Sur guest OSes, the keyboard works normally for VMs that are freshly booted. However, suspending and then resuming a VM results in the keyboard not working. No keypress events are propagated to the VM. I see this 100% of the time and the effect occurs in multiple VMs. The Big Sur version is 11.5.2; that is also the host OS. Unlike some other reports, my trackpad continues to work normally after resuming. I submitted a technical data report as well.