If someone has broken ebay https they will surely be able to catch the whole password at the end.
As others are saying, using a GET request embeds that password in the URL, which means that server logs on eBay's side will have your password in them. Server logs aren't always the most protected thing in terms of locking down systems and permission management. On the flip side, most server logs do not have POST/PUT data logged.
Edit: They do also send GET ... that is worse.