No.
The deposit is a liability, not an asset. UB didn't sell any deposits. For UB to transfer a deposit to another bank, they need to transfer money to that bank.
So if you have 100k mortgage, fully offset, UB transfer 100k to another bank for the deposit. Then they transfer the loan, and get 100k back. So the net effect is the new bank has got nothing except the potential that the customer will want to get their 100k back out at a timd outsude the banks control, typically at a very low tracker margin.