I'm not sure how long it's been in effect; I'd say at least a year now.
And it doesn't apply only to new holders of PayPal accounts - even long time account holders, if they begin having issues with their account
(such as an overabundance of buyer complaints), PayPal will not allow that account holder (eBay Seller) to withdraw funds from the account.
In other words, PayPal will put a "hold" on the funds for a time.
So if a genuine issue develops, and an eBay Buyer files a complaint in the PayPal Resolution Center (which must be done in a timely manner)
against that Seller, eBay/PayPal are in control of the funds. If they decide in favor of the Buyer after looking things over and hearing from both sides,
they can simply send the "held" funds directly back to the Buyer.
It's all spelled out in PayPal's "Terms of Use"; there are no unfair surprises for the crooks who would attempt to scam buyers on eBay.
(BTW, I'm assuming everyone here is aware that eBay owns PayPal.)