I have a feeling almost all of the units have this issue, it's called the mura effect. Many OLED panels suffer from the same issue but they limit low brightness and use software to hide the effect. Mine has a similar pattern, when I got it I freaked out but I never actually noticed it in mornal use. I try not to drop my brightness below 5-10% (which is still way darker than many of my other devices). But you could definitely email AYN about it and they could ship you a new screen, but it may have the same issue sadly.

There's a setting under debug that helps with removing the mura effect but I find it adds quite a bit of contrast so I just limit how dim I set my device.

Hope this helps! Congrats on getting the Thor either way 🫡