How to get back colored app headers in recent apps list on Samsung devices running on Android Oreo?
It looks to me that this is not possible, because Oreo re-used the color coding for different purpose:


white header: standard app


and here, the original coloring concept is partially present in text color (instead of bg color)

light cyan header: app pair on split screen




I think that this new coloring purpose implies that the original coloring is gone.