Username definitely should definitely stay in the account section. Account information pretty much universally includes account name (username), password, email address.
Profile is definitely more of the personal things (like bio).
I’m just going to add my voice here that I couldn’t figure out how to update my profile picture. I was on the profile page where all the rest of the profile information that shows up on my user card etc was editable, but no place to change my profile picture. Very confusing.
Also, if I want people to fill out their profile, they should really be able to do so on one page. All the other information on the account page is required at signup. But if they signup, and then I direct them to fill out their profile page, they will still never have had the option of specifying a profile picture. (We are not allowing social media signup, and lots of people don’t have gravatars.)
I think name (not username) and profile picture should be moved to the profile page.