You’ve just posted your email here … on a public board.
There are many possible reasons why your personal information may appear on the dark web: use of third part apps, logging in while using public Wi-Fi, carelessness with your data, etc. As there’s been no report in the media about a data breach in eBay, no notification has been given to members as required by law, no numerous complaints by members of their data having been taken, it is not likely that eBay is the source of your data having been obtained.
Websites don’t monitor the web for their members’ data, by the way. That would imply that websites have a duty to your data beyond the confines of their security within the confines of their site, host, servers, data transmitted or received or held by them… which is self-evidently beyond their purview. Your login credentials for eBay are your responsibility if, for instance, you log in to your eBay account at an airport on public Wi-Fi or on a compromised device.
