Yes, soft molts are natural in growing chicks as they will lose baby down for baby feathers, then lose those for teen feathers, then those for adult feathers. I will often see tiny little feathers here and there and the babies have loose fluff on them and some thinninsh spots here and there as down and sparse feathers
cover an area. So they often look pretty scraggly from the time they lose the baby down fluff until they get in the teen feathers (like a really bad hair day). Roosters will look more scraggly than hens as hens grow their adult feathers faster (especially tail, back and wing areas). Faces, necks and chests seem to feather more slowly and can have some bare-ish spots.
However, if you are seeing big bald spots on your chicks with lots of feathers lost on the ground area, that may not be normal. I've never witnessed big bald spots (like a naked back) on my growing chicks from a hard molt. I've only had my older hens experience a hard molt like that. A hard molt in chicks could signal a dietary deficiency, too warm a brooder (heat lamps), or cramped quarters (stress).
Since you have chicks with a momma and all seem healthy, it is likely a soft molt as you don't seem startled that you have naked chicks.
BYC has a good molt article here:
https://www.backyardchickens.com/a/chickens-loosing-feathers-managing-your-flocks-molt
The Chicken Chick has a good article on causes of unhealthy feather loss here:
http://www.the-chicken-chick.com/2013/03/chicken-feather-loss-cannibalism-causes.html
HTH
Lady of McCamley