Tested and it works fine. I made this for people that want to change their username on public Invidious instances without having to create a new account or having to contact the instance maintainer to change their username. It also updates the materialized views sha256 ids, so if a user changed their account name from user to user2 and a new user registers on the instance with the username user, there shouldn't be a relation collision (when the collision happens, this is displayed: relation "subscriptions_sha256" already exists)

Tested:

• Changing username from user1 to user2, subscriptions are maintained across username changes
• Playlist author (for Invidious playlists) updated on username change.
• Changing the username from user2 back to user1 works well.
• If the user tries to change their username to one that already exists on the database, a "Username is already taken, use another one" will be returned. (Although someone can still register or change their username with an already taken username but with a slight unnoticeable SPACE character on it, it's possible to have a user called user1 and user1 )