Tortoise skin peeling in flakes: normal shedding or too dry?

The version that is not normal is skin that is very dry and cracked, or constantly flaky rather than in cycles, which usually means hydration or a dry enclosure. Regular shallow lukewarm soaks, fresh water down every day, and a burrowing area that holds some moisture even if the rest is dry.

Since you are already soaking her and she looks well underneath, you are most of the way there.

Normal, and the soak is doing you a favour rather than a disservice. Tortoises shed in small bits and flakes rather than in one piece, which makes a perfectly healthy one look ragged round the neck and legs. Growing animals do it more often.

The extra flaking after a soak is just the water loosening what was already on its way off. Healthy skin underneath plus an animal that is eating and active is the whole reassurance.