I don't think people worry too much about banding on test patterns.
The banding is seen in real world contents (movies, football etc.). Some of them have a clean panel almost free of these whilst some don't.
That one 1 cm band on mine shows up to 40%. This is the one that shows in football and movies frequently. The remaining 4 or 5 of them are quite faint.
Sorry to read of your continuing issues.
Of the 5 OLED's I have owned ALL of them have had banding. However the one I currently still have (2019 panel) is only noticeable in specific dark grey scenes, i.e its very rare you'll see it.
However the reason I'm posting is: the 83" C1 evo panel I had last year, had negligible banding in dark grey scenes, BUT, banding in bright HDR elements, like a very bright sky. Mainly noticeable when panning. Bad enough that I returned it. My Z9J is the cleanest TV I have ever owned - but yes you might get occasional light diffuse blooming which is visible again in certain panning shots.
I guess what I'm trying to say is, all TV's will have some downside in my experience, but the tough decision is whether you personally can tolerate it. If not, return it for sure and don't look back. You'll get a TV you're happy with, sometimes it's just a pain getting there.
