Your Staking Rewards Account is custodial (unlike the funds you store in your DeFi Wallet, which is non-custodial), so it is not backed up by your wallet's backup phrase.
However, your Staking Rewards Account is associated with your identity profile. Thus, if you have lost your password, you can recover your wallet here using your 12 words recovery phrase and proceed with account verification again in order to access your custodial funds, including funds in your Staking Rewards Account.
If you have lost your password and your recovery phrase, you will still be able to recover your custodial funds, including funds in your Staking Rewards Account, however, the funds held in your DeFi Wallet will be lost. For more information about account recovery, please check this support article.