I use it, I have a 5Gig plan in the sim and never ran out. I do regular long range flights with no RC connection so it should be eating up Data pretty fast but I always have a 4G connection
Those old drones are not bound and can just be sold and logged in with a new account. It's mostly on the Fly app with newer drones from Air 2S that were bound to an account.
If you are the original owner, on the new RC log enter your old email used on the previous RC then select reset password. This should allow you create a new password and use the drone IF you are the original owner.
There is one way. If you have care refresh just damage the drone and send it back for a replacement which will come with a much older version of FW, then just update till 0600. ;)
Here you go but need to use Drone Hacks app in Windows to downgrade it.
https://www.dankdronedownloader.com/DDD2/app/index.php?Brand=DJI&model=wm261&ver=01.01.0600&type=Aircraft