Google rewrites titles on a meaningful share of queries, usually when the original is stuffed with keywords, duplicated across a template or unrelated to the query it matched. Writing a clear, specific title that reads like a human wrote it is the most reliable way to keep your own version displayed.
Aim for roughly 50-60 characters before truncation, put the distinguishing term first, and make every title unique across the site. Duplicated titles across hundreds of pages are one of the strongest signals of a thin template — and one of the fastest wins available, because fixing them changes click-through without changing rankings.