If you are a Destiny fan and have Destiny 2 on Battle.net you've most likely already linked your Battle.net and Steam account to transfer your game on October 1st. That said, if you picked up Destiny 2 for free on Battle.net you might not have transferred yet and you should because Destiny 2 on PC won't be available on Battle.net for the long haul. Bungie has parted ways with Activision and is now flying solo and migrating to Steam is part of the separation. At some point Destiny 2 is going entirely free to play but if you have any account data in Battle.net now is the time to move it over to Steam.

I moved things over and it wasn't too hard. Frankly having Destiny 2 on Steam is something i'd prefer over Battle.net anyway.

https://www.bungie.net/7/en/PCMove