I moved to another phone. I can’t access my wallet. Why?

You pravite key is stored locally in your mobile device and secured by secue enclave. 

If you change to a new mobile, you will need to recovery your key into your new mobile. Process, remove the read only wallet from your new mobile, import your  wallet through seed phrase.

If you delete your wallet from your old mobile without backing up the seed phrase, you lose everything in that wallet, and there is no way to recovery.