We live in an age of exoplanet discovery. One thing we've learned is not to be surprised by the kinds of exoplanets we keep discovering. We've discovered planets where it might rain glass or even iron, planets that are the rocky core remnants of gas giants stripped of their atmospheres, and drifting rogue planets untethered to any star.
It is stated in the article that it is a “second generation planet.”. The primary star went red giant and destroyed all the previous Exoplanets. The one they observed has reformed from that debre.
It’s a preprint tough, so not yet peer reviews. So for now maybe to be taken with a grain of salt.