Can someone help me understand why my 4yo would rather be with her dad?

I just want to say, I know this isn’t a competition. By the title I know it can seem that way but I’m really just trying to understand.

So my ex husband and I have 50/50 custody of our 4 year old, two weeks on and two weeks off. She is always really happy to see me but after a couple of days she is BAWLING saying she wants to go back to her dads house. I know she could just be a daddy’s girl but I’ve never met a child who didn’t want to stay with their mom. It just really breaks my heart because I try my best to make sure she has a good time over here by taking her to the playground, arcade games, painting, baking together, getting her some of her favorite toys, etc.. BUT it always feels like I never do enough. Sometimes I feel like she doesn’t love me. 😔 She’s with me right now, I put her to bed and she cried asking for her dad. I told her she’d see him in a few days and this is exactly what she said “I miss my dad and my momma” by momma she was talking about her step mom (I’m fine with that). I feel so depressed. I just don’t understand what I’m doing wrong? I feel like she is lacking something here to make her not want to stay but I couldn’t see what it is. I give her my time, I always make sure she has what she wants & needs, I try my best to make sure she has fun.

In our household, it’s her step dad, me, her little sister and herself. At her dads, it’s her step mom, her dad and 3 step siblings. And yes, she does get along with my husband. He’s been in her life since she was 1 and she calls him daddy as well (not forced, that was her decision). Just to be safe, I’ve asked her before “Has mommy ever done something to make you sad or mad?” And she said no. I said “Has anyone in mommy’s house made you sad, mad or scared?” She said no.

So please I really don’t understand. Is this normal? She started Pre-K this year and we chose a school in the middle of us. My ex husband originally wanted her to go to school where he lives (we live 35 minutes apart) because he said it would benefit his work schedule. I said no because I didn’t want to only see her on the weekends but I’m starting to think maybe that would’ve been best for her. She obviously doesn’t want to stay with me 😔 I just want to make her happy is all.