Bip39 Mnemonic. Firstly you need to keep it SEPARATELY from your seed. Acquiring your seed and your passphrase in precisely the same area defeats the purpose of aquiring a passphrase to start with. Entropy is a sophisticated element. Your mnemonic might be insecure if this aspect is employed improperly. Read https://natural-bookmark.com/story19003905/bip-39-https-linktr-ee-bip39-what-does-ian-coleman-bip39-mean