Will we ever find out what this actually means in our lifetime?
From ["Not all fast radio bursts are created equal"](https://www.nature.com/articles/d41586-019-03894-6), 2020-01-06:
> Curiously, because the luminosity of a typical quasar is not dissimilar to the peak luminosity of an FRB, we cannot yet completely discount the involvement of supermassive black holes. But Marcote and colleagues’ results argue against that possibility, and the timescales for quasar variability are more likely to be days to months than milliseconds.
Wikipedia has a [section on hypotheses](https://en.wikipedia.org/wiki/Fast_radio_burst#Origin_hypoth...).