I'm reading this article of Scientific American.
Here is some of sentence.
In 2017 they published a study with a number of theoretical calculations that suggested a magnetar would first produce a superluminous supernova—and then, years if not decades later, produce a number of FRBs (although exactly how remains a mystery).
I can't understand what years if not decades later means really.
Does it mean a magnetar produce a number of FRBs after few years?
Thank you in advance.