Thralls left behind from decayed bases never vanish. Since players can’t kill them they linger - FOREVER. There should be a decay timer on thralls left behind. Also, once a base decays, if there were thralls left on floors above ground they remain hovering in the air.
Yes, I’ve seen a LOT of thralls just floating everywhere in the map where bases used to be. This can affect game performance in PVE. They need an autodecay timer.
It was put on the future updates that they’ll “nuke all of those thralls out of the sky with a future update.” It is an inconvenience at the moment sure but I only notice a performance issue when there are more than 6 in a close proximity of each other but it’s more or less a minor frame skip or two for a brief moment and then back to normal.
You can get rid of some of them if you get bored. You can kite some world bosses to them. It’s been working for me in the highlands. I use the Rotbranch. I have some screenshots of my server with 30 or more abandoned thalls in some areas, it doesn’t help with lag having that many hanging around.
This is the right answer!!! and if they are in the sky, make stairs for the boss to get up and kill them
you can also do this to your neighbors base while he is offline (works best with purge bone dragon)