Shared a one-time code — account taken over

Someone in a chat asks to 'send you a code to confirm you are real'. That code hands over your WhatsApp, Instagram or email account, which is then used to scam your contacts. Warning signs: A code you did not request; Somebody needs it 'just for verification'; A known contact suddenly writes differently. What to do: Recover the account at once, sign out everywhere, enable two-factor with a PIN and warn your contacts. Typical loss: 0–2.000 €.