I found a strange possibility in options screen menu.
When you press and hold CTRL key on screen you will see additional marks, I don't know what it is, maybe some debug information.

"565" and "X888" are just references in Direct3D to colour formats (16-bit and 32-bit). More of an easter egg than a bug.

Thanks for the explanation.
So as I thought are a debug information which Scawen forgot to remove.