As mentioned by the Ancient One in Avengers: Endgame, if you don't return to the exact moment it would affect reality, so shouldn't Gamora from 2014 return not to affect the reality/timeline?
What the Ancient One was saying is that if the stone is removed from the timeline and never replaced, then that reality branches off and creates another reality where that stone doesn't exist. She visualizes this to Bruce by the golden string that branches off with a black string. If the stones are taken from a point in time, but then put back at the exact same time then nothing changes. That is why there was such a focus on returning the stones to their original timelines. This is what Hope and Scott were trying to get the van up and running for, and it's what Steve Rogers does at the end of the movie.
Now, 2014 Gamora, 2014 Nebula and 2014 Thanos have left their timeline, so theoretically the reality they were from has branched off into a reality where they no longer exist, but we don't see this. We don't really learn enough from the movie to know what this means, but it's not important for us as it's not in the reality/timeline that we saw.