I posted about this a few months ago. Through some sheer brain dead dumbassery on my part, I sent 3.32 ETH worth $9000 to an Elon Musk crypto scam a few months ago.
My Coinbase account will show it as a withdraw, but it was lost to a scam.
So when Coinbase sends me a 1099-K or whatever the tax form is, how can I allow for this as a LOSS, not taking a profit?
Have you got a police report filed? If not, please do so at your earliest convenience. That will help you to prove your point in case you receive a notice from IRS.
If coinbase account is showing the transaction, there is a chance that you will need to prove the point in case IRS asks for it. But ideally the tax is calculated on the converted amount. But in your case, you will need some legal documents to prove your stand.