iMac 27" late 2013 here. Shortly after updating from Sierra to Mojave, I noticed that any windows or applications left open for 5 minutes or longer are producing some very noticeable image ghosting on my display. These artifacts intensify over time, and show up as reddish images that are clearly of the open windows but not fully complete duplicates, and change depending on what has been open. Running a screensaver or turning the display off will cause them to fade, but nothing I've done so far has prevented them from recurring almost immediately. I tried booting into my emergency partition, which is running 10.10 Yosemite, to see if I could duplicate the issue:; after several hours of trying, things remained normal as they had been before the update to 10.14. so I can only conclude that it is a software issue. After doing some digging, I found that people have been reporting this issue on High Sierra as well, and that it may be Metal-related, but if there's a fix short of backdating the OS I haven't found one. Has anyone else experienced this? And has Apple said anything about it at all?