My editor was really good about going over content changes with me, so I was very surprised when I got the finished copy of my book and noticed some changes we hadn't discussed. It looks like they've just pulled words and sentences out at random. In one place a whole paragraph got cut to one sentence and put with the paragraph before it. Some words were changed to synonyms that aren't any better than the words I had chosen. Why did they do that? (Talk about things that don't make any sense.)
Did you discuss changes before or after your book went to typesetting? If it was before, then those changes were probably made during typesetting to get it to fit the page better.
Books are printed in signatures--a very large piece of paper with 32 printed pages that when folded create a section of your book. The goal of the typesetter is to make your book fit into multiples of 32 pages. To do this, sometimes they have to cut a word or two out of a paragraph to save a line; or cut a full paragraph to save a page. A really good typesetter also has good editing skills so they can do this without disrupting the flow of your story or changing the intent of your words.
There are also things called widows and orphans. A widow is the last line of a paragraph that is all by itself at the top of a page. An orphan is the first line of a paragraph that is all by itself at the bottom of a page. These aren't good. I also don't like the aesthetics of having just one word as the last line of a paragraph. Sometimes typesetting can control that by smooshing the space between the words and/or the letters a little bit (called kerning and tracking), but if that doesn't work, they have to pull out a word or a sentence to make it fit.
So look at the places where the changes were made. Is the last line of the paragraph nearly the full length of the page? Does the chapter end at the bottom of a page--or very close to it? If so, I'm betting that's the reason.