I'm guessing it's because they have stopped using PayPal as their main payments provider, they switched to a Dutch company named Adyen.
I was forced to open an online bank account just for eBay. No way do I trust them with access to my main account. Among other things, the whole process had me go deeper into my eBay account than I've been for a while and I noticed how sloppy some their coding is and how easy it would be to find the answers to their security questions, almost all of which could easily be found out with a public records search if you knew the identity of the account holder.
Just because the correct security question answers may be publicly available. One doesn't have to answer them correctly when setting up security questions.
I realize that but most people don't and it means lax coding and ignorance of some basic security concepts on their side which is pretty bad considering the monetary value of their service. The do have a good knee jerk response when they think your account has been hacked that I discovered by accident when I messed something up in updating my account information. My account was immediately locked and I was given a phone number and reference code. A human being answered the phone right away and I had to verify myself over the phone in pretty much the same fashion as a bank would do.