TCL 50S535 bad tcon or panel issue?

[x_orange90_x]

I see, it sounded like you meant they tested bad.

Even though I don't understand how the main board could cause this type of display issue, I'm going to try disconnecting it and getting a test pattern on the tcon. Depending on the shades of colors in that pattern I may not see the band anyway 😒

It just doesn't make sense that it appears in some shades but not others, particularly in light but not in dark.