A photo taken at the brief moment this screen appears during shutdown sequence, right after a brief black screen. This is a new iMac 27 with AMD Radeon Pro 5300 4gb graphics.
The scary thing about this showing up is that I just retired a 2011 iMac 27 after enduring months of a left side of screen pattern malfunction on start up. The old screen had intermittent vertical stripes of variable, sometime brilliant colors on the same left side (only) of screen, that would usually go away after a while. Eventually the hard drive failed without addressing the graphics issue, so a new machine is now in place (<2 months) and the picture here is what i see at every shutdown. I can return this machine due to Costco return policy, and plan to do so.
Anybody here have this experience? Are they all doing this?