Thank you for posting that screenshot.   It's a newish scam.

We have seen members using the message system to pretend to be ebay and get bank details  but never actually seen how the message box within an offer is used to scam, although someone else reported it happening.

In case your post gets edited, for the benefit of others, the message box is as if ebay is telling the seller that the buyer has prepaid but the seller's account needs verifying and there is a link to do that.  Clearly the link will then steal bank or card details. 

You did well to spot it, but there is no use reporting the account as it will be entirely disposable.

kat@ebay 

Another scam to add to the ebay message one.