Appears to happen in some Syntakt, don’t know if the cause has been pinned down but there’s a thread about it. Here, from the same thread, is a post regarding AH+FX (they seem to share the same display part):
You should probably read through the thread, there may be some relevant information because I don’t know how this relates to warranty or if there’s a known catalyst which causes the OLED banding.
At least worth taking a look and I guess if it helps, you’re not alone. Good luck.