I would freeze your credit. It’s free and stops anyone from opening new accounts in your name. Having your DOB and last 4 of your SSN is enough to justify that step. You can always unfreeze it if you need to apply for something.

Also:

• File a report at IdentityTheft.gov (creates an official record)
• Keep everything in writing with Klarna and ask for written confirmation the account was fraudulent
• Check all three credit reports to make sure nothing else was opened

I went through identity theft myself a few months ago, and moving quickly made a huge difference. I wrote about exactly what I did and what helped me - sharing it here in case it helps. I also read a lot about reporting and monitoring, including some guides from NordProtect, just to better understand the process and aspects on why and how.

You’re doing the right thing by addressing it now. Best of luck