Is this shell rot?

Hello,

He is around a 20 year old male red eared slider. He’s active, eats, and has a proper basking area with the right lights. He is also in a super undersized 30ish gallon tank but will be in a more proper 75 gallon tank this week. The white spots don’t feel soft/squishy and do not smell. He also has several unshed scutes as seen in the first photo. Thanks!