The token reached Discord but was rejected at login with a 401 or 'Improper Token' error.
The token is revoked, expired, belongs to a locked or flagged account, or got malformed during entry. Discord accepted the connection request but refused to authenticate the token.
Regenerate the token in Discord (User Settings, Reset Token) and update .env. Verify the account isn't locked or requiring verification. Make sure you copied the raw token, not the OAuth URL or client secret.