vSphere 7.0b was just released last week and one of the important fixes was to resolve an issue where Nested ESXi VMs were crashing upon powering on an inner-guest VM. This looks to have also affect newer generations of CPUs including Intel's 10th Gen Comet Lake which is also found in the latest 10th Gen Intel NUCs (Frost Canyon).
A number of folks quickly found that if you simply applied the ESXi 7.0b patch, an unexpected behavior occurred on the 10th Gen Intel NUCs and the onboard networking was lost upon a reboot. This occurs as the original ne1000 driver which had been replaced with a newer version found within ESXi 7.0b no longer recognizes the onboard Intel NIC. The solution is quite simple, create a new Image Profile that contains the Intel NUC NIC Driver.
Several of you have asked for instructions and although this is a pretty common vSphere workflow, I have documented the two supported options using the vSphere Image Builder utility but there are definitely other methods which will have the same results. If you have access to a vCenter Server 6.7 or newer, I recommend using the Image Builder UI. If vCenter Server access is not available, then you can use Image Builder with PowerCLI, however you will need to have access to a Windows machine as the Image Builder cmdlet is not supported with PowerCLI Core.
Note: To prevent this from happening in the future, I am also working with Songtao, the developer of the Intel NUC driver to see if we can rename the VIB which should prevent this from happening with future updates.