Beber said:

Well, when watching the whole movie, some shots felt a little off to me, and since you're using various sources, I guess this is inevitable. And this one actually felt off to me in terms of definition (like the very last shot leading to the ending credits), grain, etc. in the continuity when comparing to the preceding scene.

This can only be prevented by adding artificial grain throughout the whole movie which may improve the viewing experience but is destruction of picture information. I also expect that the difference is less obvious at higher bitrates.