Bip39 Checksum. Keep in mind, there is absolutely no this kind of matter for a “Improper” passphrase. Just about every distinct passphrase you enter is a fully new wallet. Be mindful when recovering your seed which has a passphrase. Any one else who discovers the phrase can steal the bitcoins. https://wisesocialsmedia.com/story4898034/bip-39-https-linktr-ee-bip39-bip39-wallets-things-to-know-before-you-buy