I typed my passphrase wrong and my wallet opened a different one: is that normal?
You typed your passphrase with a typo and the wallet opened something that isn't yours, with no error message at all: it feels like everything is gone.
BIP-39 **has no wrong passphrase**: any string you type generates a valid, different wallet, with no error or warning.
Why your wallet doesn't warn you about a wrong passphrase
BIP-39 is designed so that any passphrase, even one with typos, produces a valid seed. Technically, there is no 'wrong' passphrase: every one derives a wallet.
The source says it literally: "every passphrase generates a valid seed (and thus a deterministic wallet) but only the correct one will make the desired wallet available". So each string you type opens a different wallet, but only the correct one shows your funds.
What you see when the passphrase isn't yours
When you enter a wrong passphrase, you'll normally see an empty wallet or a transaction history you don't recognize. There's no error because, to the system, that wallet is just as valid as any other.
That doesn't mean your backup failed or your bitcoin are lost. It means you're looking at a different wallet, derived from a different passphrase.
How to get back to the right wallet
Try again with the exact passphrase, respecting uppercase, spaces, and symbols. A single different character takes you to another wallet.
If you have a note of an address you know was yours, compare it with the one the wallet shows after restoring. If it doesn't match, you're in the wrong wallet.
No error does not mean you're in your wallet
If you used a passphrase that's similar but not identical, you enter a different wallet. It may be empty or show transactions you don't recognize. That doesn't prove your bitcoin disappeared: they are in the wallet that corresponds to the exact passphrase you originally chose. The problem isn't that the wallet failed; it's that the passphrase you used isn't the original.
Source: BIP-39