It lets you switch back and forth between the custodial wallet and self-custody wallet. The custom address stays associated with the custodial wallet and you get a randomized address for the self-custody one. If you decide to try it, just make sure you still have the email address associated with your custodial wallet in case you need to recover it, but when I updated to the TestFlight it kept me logged in and I’ve switched back and forth between custody and self-custody wallets with no issues so far.