Naw it's not that, the big one came with bumps, the 2 little guys I've had them since hatchlings. I also wonder why they look pyrimided in pictures. In person the look perfectly round. I see what you're saying but no, I have closed chamber with 80%to100% humidity. If you scrape the top soil it's dark moist soil underneath.
I also soak every two days sometimes daily
Little baby torts IMO should be #1 kept warm, never below 80F , #2 be soaked DAILY. A sick baby tort #1 bump up the temp to 85F with 90% or more humid AIR (not substrate) and soak in 95-105F warm water or carrot food (if baby not eating) even 2-3 x day. That’s what I would do. I had a sick baby tort and today he is a 7lb eating monster. I wish you best of luck and patience. Tortoise recovery maybe a slow long process