…the only thing I noticed was that in some portions there are 4 corners of the frame that show some type of blur, hardly noticeable but I thought I’d mention it.
The 4:3 version isn’t full width and the 16:9 isn’t full height, so that means the corners lack a little information because neither version can supply everything (because if one of those had all the information then there’d be no need for hybriding like this 😃). The blurred material in the corners in this hybrid version is filling that’s intended to make the corners’ missing information not as obvious as solid black (boxes) would be, is a “best that can be done here” trick as it were to make the viewing a little smoother.