The issue isn't so much 'burn in' as 'burn out' or more uneven wear. Each sub-pixel has a certain life span and having a red logo, which only uses the red sub-pixel and on continuously causes those to wear significantly more than the rest of the red sub-pixels that are varying in intensity and can be 'off' too if the colour displayed doesn't have any red in it.
This is why you see the logo only affecting the Red slide. The Red sub-pixels have worn out. Obviously it can affect the Magenta (red and blue) and Yellow (red and green) slides too because the Red is no longer present so the area looks Blue or Green. On grey slides, the area is Cyan because there is no more red.
It really depends on the life of the individual sub-pixels and the logo on screen. It's also why its a cumulative effect - it doesn't matter if you only watch an hour a day with other content watched in between - that hour adds up to 7hrs a week, 365hrs a year etc of wearing those sub-pixels faster than the rest. Its worse with a single colour (Red, Green, Blue) because these are using just 1 sub-pixel and intensely to get the brightness. White logos use all 3 sub-pixels equally so the work load is shared and some logos are more a transparency too.
If you only watch 21:9 ratio content, eventually the middle of the screen will be 'dimmer' because these sub-pixels will have worn more. Then when you watch full screen content, the black bar areas will be more noticeably brighter because they have had much less use and therefore not worn.
Burn in would require a static image to be displayed continuously without turning off or changing channels. OLED TV's, I believe, do have safeguards in place to minimise that risk, such as dimming the screen, using screensavers and/or pixel shifting but its much more difficult to even up the wear. Individual sub-pixels may start off with the same amount of 'Life', but certain things can cause them to burn through that life faster than the rest - such as static logo's/boxes etc - because they have to be on continuously.
If you look at the CNN red Slide (max brightness) on the RTING's test, its clear that the Red logo has used up the life of the Red sub-pixels in that area. However, you can also see where People are on screen.
You can see that in some areas, the red has worn out completely - so we get 'black' but if we go to the Magenta slide (red and blue), we see the black become blue showing that the Blue sub-pixels are still working...
This is indicative of uneven wear rather than burn in....
Compare that Red Slide to the one at regular Brightness...
You can see that despite displaying the same content, the red slide shows much less wear/deterioration. This again is to be expected as the sub-pixels are not being used as intensly/brightly so therefore not wearing out as fast. A candle that burns twice as brightly burns half as long... A lightbulb used with a dimmer switch lasts longer than one that's on full too...
Sony have guidelines to minimise this - zoom in on 21:9, don't use EPG's (or be very quick) etc. All things to keep the wear more even across the panel. Its not just a Channel logo that can affect the evenness of the wear but watching news with ticker tape scrolling which is still moving, EPG boxes and, as this shows, even moving people such as a newsreader, can wear certain sub-pixels faster than the 'background'.
The problem isn't 'burn-in' on the traditional sense so its not about limiting your news viewing to an hour or two a day and making sure you have the screen wash active. Its still going to cause more wear to some sub-pixels compared to the rest and the more you watch, the bigger the difference in wear becomes. The sub-pixels have a finite life so if they are being used more and brighter than the others, they are using up more of their life and thus will fade until eventually they cannot illuminate at all. It will happen to ALL sub-pixels eventually - its just that some content causes that to happen to certain areas quicker - thus this is 'uneven wear' rather than burn in.
I don't know what the solution is, who is at fault or should be made accountable. I do think that maybe OLEDs are NOT the best technology for everyone - certainly not for those that watch certain content with constant regularity - maybe not those with Kids that watch NickJr for a couple of hours everyday for example or spend hours looking through Netflix to find something to watch. At least with Netflix, I guess you can look on other devices and add to 'my List' to minimise the amount of time that Logo is on screen.
There is no denying that OLEDs have amazing PQ but by design and the very nature of content will lead to uneven wear. An image isn't consistently using all sub-pixels evenly so there will be uneven wear - its whether or not the wear will even up over time or whether you continue to display certain content that is wearing out certain sub-pixels faster so that gap becomes larger and larger until it becomes noticeable....