Baby powder is not recommended to use on babies and toddlers because the baby powder can get into a girls vagina and possibly cause ovarian cancer.
That is for baby girls because when you sprinkle the baby powder onto the baby girls vagina it gets mixed in with the pee and then can easily get into a girls vagina as they sit in the wet diaper.
For baby boys the risk is not there but still a baby boy could breathe in the powder from the baby powder being sprinkled onto them and then it can cause breathing issues.
I never used any baby powder on my kids when they were in diapers as it really wasn't necessary.
The baby powder is supposed to help absorb moisture from the babies skin but that is not much of a problem today with the disposable diapers.
Disposable diapers absorb the urine anyway and the skin feels dry unless the diaper is either leaking or about to leak.