I had not problems with the boxed corners on my Note 8, 22U or 23U...
I didn't own an 24U but when I see it on displays, the corners look to have more pronouncedly sharper corners and don't care for them. Probably being thicker didn't help the look but that's me,
Holding display S24 and S24 pluses I was surprised how nice in hand feel with the rounded corners so I hope the S25U will feel the same. Also prefer flat screens so if I do get one I can finally get a tempered protector on it without needing to use liquid adhesive to install and pay $60 for.