Hello, my Pro1x also has a black spot, I also find it very annoying, yes, at the top edge it doesn't really bother me, but...!
I also have to say that it doesn't work as expected.
The camera is total crap. With the original app it rarely or never focuses and the Manuel Camera DSLR Pro app often freezes, despite being a paid version. Not nice. I want my BlackBerry Key2 back. It just worked and always worked. It was just that Android 8.1 was too old.