You must have ticked the box for :
Private listing (Keep bidder and buyer identities hidden from the public. ) |_| Allow buyers to remain anonymous to other eBay users
in the middle of the payments section on the Advanced Listing form (no idea if using the Quick listing form or if that option is even available there)
It is a per listing setting, so you need to revise all the listings where it might be set. Unfortunately, there are no search filters for private listings, so you need to open each one and look at the very bottom left for text indicating it is private. You can bulk edit that option, but it has to be done individually not in one pass.
See here:
https://community.ebay.com/t5/Archive-Selling/Turn-all-your-listing-to-private-at-one/m-p/23940883/h...You can't do anything about already sold listings - they will remain private.
