G.♣.
It's good for the daycare to let you know that she has been eating less so that you are aware of it. It doesn't necessarily mean there is a problem or that you need to DO anything. It's more that if you have any concerns or notice any changes in her that you have the information that you would need to give the doctor.
The eating habits of children, and especially toddlers, change so much. They can be starving one day and eat more than an adult, then be eat no more than 2 or 3 bites the next few days.
Right now, it's much more important that you teach her HOW to eat. She does need to learn how to feed herself. She also needs to understand what it means to be hungry. Offer her food, let her eat what she wants and if she indicates to you that she's done, let her be done. It is just so important for kids to learn how to listen to their bodies. If her body is telling her she is not hungry, go with that. When she's hungry, she'll ask for food - or you'll know because you have a very cranky kid! (We always joked, it's time to feed the monster!)
It is important for her to learn how to feed herself, even if she makes a huge mess. This is something that is expected of 2 year olds. My son started going to daycare when he was 18 months old, and he was expected to drink out of a cup! He knew how, but I did not realize that was an expectation of a child who was only a year and a half old.
Daycare does need her to feed herself, though, as they have many, many kids to care for and don't really have the time to feed each of them individually.