Daycare Diaper Changes

Asking for advice on how to address this.. my son is 21 months and I send 8 diapers a day to daycare. I always count how many were used when we get home. In a 9 hour period daycare only used 1 diaper. I know he is usually wet when he gets dropped off since he just had breakfast. He has a small diaper rash that is sore.

How do I address this with daycare nicely?