Yes, when you go offline the other vaults in the neighborhood notice and send messages to the folks who need to pick up the slack created by your vacancy… The new “neighboring addresses” then request the chunks they need from the other vaults that have the remaining copies of them.
There are no PUT fees attached to this. Farmers are paid based on GETS not puts.
My understanding is that vaults are now non-persistant, and if you turn yours off you come up empty and with a new address next time. Non-persistent vaults - #6 by dirvine