It's a new word. If you look it up, you'll find more than one meaning. Initially, it appeared to refer to cheating on your partner while in quarantine. More recently, the term is being used to describe people who are simply not following adequate quarantine and endangering others, usually their immediate family.
This has actually been a problem we've seen in the office with older couples. One spouse will be furious at the other because they won't wear a mask or
they spend everyday at a different store or with others who refuse to isolate. It can get pretty tense!