8bit skull displayed on RDP login

When logging into a system via RDP what looks like a skull may be momentarily displayed:

After some testing, I believe it's caused by a slow transition from the user icon from the lock/login screen to the actual desktop, and during the transition that user icon can become an 8bit image like you saw. During testing there were a couple of time when the user icon would start to change into the "skull" but never completed because it went to the desktop too quickly.