I would imagine the same thing that prompted WoS to back out of the U.S. plays a factor in ending the custodial offering. After all, I believe that was when Alby went invite only, too.

However, it sounds like they also didn't want to have to maintain a large node with a ton of liquidity locked into lightning channels to accommodate the number of people using their service, some of them for over 1m sats at a time before transferring to cold storage. I must admit I was one of the lunatics doing so.

Instead, they are offering various ways for you to hold your own keys and take advantage of the browser extension UX + Lightning address, and I hear a mobile app is also coming. Only one of those ways requires payment.