It very much sounds like a scam call to me. Anybody can call you and claim to be eBay.
The only connection to Optus is that if you are or were with Optus, scammers might have your phone number now.
After the Optus data breach, it is more important than ever not to give any details to the first person who calls and claims to be a company or an organization.
At any rate, in the rare case when eBay does call a customer, they also send a message to confirm it is indeed them. Have you looked at your message box? Is there a message from eBay concerning this issue?
