Picky eater

My daughter is 3 and she goes to daycare and they feed her breakfast, lunch and snack Monday- Friday. But I have been noticing on the weekends and at dinner time she is starting to be picky. She will ask “what is that?” Referring to the food on her plate and I tell her and I tell her it’s good. She will say she doesn’t like it. Or say it’s nasty. And sometimes I would be in the kitchen for an hour making the food all for her to say she doesn’t like it. I have stood my ground and had her go to her room and come back when she’s ready to eat. But she will come back wanting to eat sweets like cookies and juice. I have two kids and my other kid eats anything in front of him. I can’t make separate foods for everyone because of our grocery budget. 🤦🏻‍♀️ how should I handle this? Is 3 too young to have her eat or not? I keep her food for when she’s ready to eat again but idk. 😩