Fraudulent Tax Filling Identified after Tax and Identity Verification. Taxes filled with HR block.

Hello,

I have, for the first time in the US, filled my taxes with an extension with HR Block and so I had a form 1040.

IRS wrote me an IRS Notice CP5071 letter 10 days later to ask me to verify my identity on the IRS website.
I didn't use the QR code and just google IRS and clicked on the google link to create my account, verify my identity and verify my tax return.

I do all of that and IRS says that Fraudulent Tax Filling [was] Identified and the refund can't not be giving…
Is that something normal when filling with HR Block ?
I guess I'll have to talk to somebody on the phone with IRS but I just don't understand the situation why this happened.
How can they say that when they knew the information on my 1040 form since when I didn't put the same information as the form, they say that it was not the same ?

Thanks !