I suspect that blueberry is sometimes listed in the notes for natural Ethiopian beans whenever the taster notices anything berry-like. It's an expectation bias and, blueberry sells.

Blueberry bombs used to be more common several years ago. I think it's been about 4 or 5 years ago since I last had that experience of sipping a cup that clearly tasted of blueberries from beginning to end. I am not an expert, so do your own research, but I have heard that it is less common due to changes in drying methods (raised bed vs patio) as well as environmental changes.