But when they are talking about breaches they aren't just referring to other web sites being hacked. In theory, your computer may have been compromised some time during the last years.

It was just weeks ago some very popular package on NPM was found to collect credentials.

Again, not saying that's what happened but theoretically your computer was breached with some malware which collected credentials. I just meant it "makes sense" from a technical point of view. The likelyhood of this being the issue I am more unsure about.