Binance: The collateral for wrapped tokens is sometimes stored in cold wallets and will be updated on the B-Tokens collateral proof page

ChainCatcher message, regarding the question of "how to manage wrapped token collateral," Binance published a blog post in response, stating that assets are always fully collateralized, receiving 1:1 support, and users can withdraw their assets at any time. Sometimes, collateral assets are stored in cold wallets that are not publicly known, or they are not transferred quickly enough to the appropriate hot wallets, which can give the impression that wrapped tokens are sometimes under-collateralized. The 1:1 support for wrapped tokens is securely held in different wallets.

Binance stated that in the coming weeks and months, users will see updated wallets on the B-Tokens collateral proof page to further enhance transparency. (Source link)