I can not log in.

[hypnotronic]

Endless log in loop seems to be happening.

[eburtonlab]

Although I am not having problem staying signed in to eBay, downdetector indicates that many users are currently having problems:

https://downdetector.com/status/ebay/

Are you using Comcast? Comcast seems to be having problems at the moment as well.

Any difference if you try using the eBay app?