Vault with consul backend issue

Hello Team,

we are facing a issue , kindly help.

Issue :
we created a new consul cluster and attached to older ILB of consul , and did a leader migration from old consul to new one , and stopped consul services in older cluster of consul.
after doing above steps , vault gets sealed and initialized becomes false , we now try to unseal with keys but it shows keys not valid.

we do not want to do vault init , as we loose all data in consul

let us know if we are following correct steps here. and help us in recovering vault.

Environment : non prod

architecture :
Vault is using consul as its backend , and vault is directly connected to consul TCP ILB not through consul client agent runnign in vault VM’s