Google has been changing how title tags from web documents appear in their search results since at least 2011. The concept is not new, Google has an automated system that determines a different arrangement of keywords or a different phrase will be better than what a page explicitly declares. A few weeks ago apparently they updated this system to a new version which started getting noticed SEOs, Google admitted to this change and told us they are now using things like Heading tags, Image alt attributes, random text on a page, or even anchor text on links to determine what the Title Tag should be.
The new changes are supposedly of higher quality according to Google, but not according to the SEOs discovering them. For example one well-known SEO, Mordy Oberstein, is currently working at SEMrush. However, Google's title tag for his page claims he works at Wix, his previous employer.
We've also seen Google changing the names of products and services to things that are unrelated or make the product/service seem to be smaller than it really is.
The only way to currently track these changes is by using the SEO module tool from the toolsuite Sistrix which implemented a new title tag tracking function after these new changes were uncovered.
Read more about this change and how to track it in this article How to Track Google's Title Tag Changes