Bip39 Checksum. Thanks to the cryptographic style of BIP-39, a weak passphrase would not lessen the security of the opposite wallets or support expose the seed words. And you need to have written it down when you were hoping to help keep a choice open up to restore your accounts. https://webcastlist.com/story20094091/bip39-word-list-pdf-https-linktr-ee-bip39-not-known-details-about-bip39-wallets