Hulu suddenly wants a MyDisney account to log in

if you also have Disney+ under a different email, that's where it gets messy. they stay as two separate MyDisney logins, one per email, so stick with the Hulu email for Hulu or it'll look like your subscription vanished. and check spam if the code doesn't show up.

You don't need a new account. Put in the same email you use for Hulu and it'll walk you through it, usually with a one-time code sent to that inbox. Your subscription and profiles come across.