An example, a third party lib I used crashed because after an update Chrome changed an optional function parameter into a required one, I am referring to this function https://developer.mozilla.org/en-US/docs/Web/API/Element/req...

So in my case I go to work and get reports that X is no longer working, lucky for me in JS is easy to patch third party code and fix this issue but I could not find a ticket that explains why Chrome did this.