This has probably been suggested before, but I think it would be awesome for players to be able to hide various aspects from other players in their campaign on their sheet.

I know, for example, in DM view we can see our player's backstory and notes, but that other players can not. I think it would be interesting to enable players to hide other things in this way. For example, I have a player whose character is a changeling. She really doesn't want the party to know that she is a changeling, but since her sheet is in the campaign on DnDBeyond, everyone can see her race plain as day. I also have a phantom rogue who is playing a resurrected prince who doesn't know he is undead, and others can see that, and so on.

I dunno, I think it would be a nice quality of life change.

I completely agree, and for the exact same reasons. In a game that is story based, where everyone has a backstory, which can create some major moments in a campaign, it's surprising to me that this is still an issue.