I feel your pain. I remember how I felt dealing with the pink stain issue on my S8+ last year. I was within my return period but at the time it was impossible to get through to customer service for an RMA. And the chances of getting another pink stained device were super high as to make the option of a return for a new device seem pointless.
Meanwhile there was a fix being promised. But when I finally got it, which with At&T meant well after the return period had passed, I found out I would be stuck permanently using the Adaptive display setting, which I hate with the heat of a thousand suns.
I am super happy with my S9+ but would not wish what I felt about my S8+ experience on any forum friend. I don't know how widespread this dead zone issue is, but if you feel it's going to trap you into a bad situation or leaving you feeling salty for the life of your device, it may be better to cut ties with it now. I don't know. I just know I really resented Samsung and skipped the Note 8 over what happened with the S8+ so I totally empathize with what you are going through.
Honestly I'm in a state of massive chaotic frustration with all of these companies right now. Not over the phones I have right this minute, but in the boneheaded directions they are deciding on at large or the crap they can't seem to get right to save their lives.
I do think Samsung sincerely tries to make its customers happy these days. But their bureaucracy sucks and they still do manage to have some pretty funky qc issues.
So does Apple, but generally, in the USA and other locations with Apple Stores, it is easier to get a sensible remedy. Usually.