Why my render borders are darker?

Really appreciate your help, because it’s an important project for me and I’m really stuck…

Actually I’m using 5.4 already, and it’s up to date. Yes I’ve heard about the 16k limitation and I’ve tested just out of curiousity and when I try more than 16k I had a specific error msg saying that 16k is the maximum limit.

Sorry not sure to understand, but when you say parts of the rendering, it means specific features?

Regarding the other thread it didn’t help me to resolve the problem… however, I’ve tried to set the “Finale Gather Quality” to the maximum and I had more arterfacts, lowering the value to the minimum didn’t helped at all sadly.