3.5yo retaliates when fun activity ends

I must be doing something wrong here. My 3.5yo is in her threenager phase and will have a dramatic meltdown at the drop of a hat. Fine, I know that's normal. What's getting to me are the intentional, calm decisions to act out at the end of an activity.

Today I was letting her play with dirt on a planting tray indoors. She wanted to help me repot houseplants and quickly pivoted to just wanting the dirt. It was a little messy, but she was trying to keep the dirt contained and even took a break to sweep up. I asked her to take her socks off because she was starting to track dirt around and then she starts sprinkling dirt on her bare feet while asking if that's okay. I say no and that we should be done and clean up now. She looks at me for a second and then calmy picks up a handful of dirt and throws it across the room. It's not a tantrum and she's not visibly upset. I think she thinks she's punishing me for doing something she doesn't want(?). I sent her to her room without her favorite stuffy while I vacuumed.

This happens in other circumstances, such as when I ask her to put her napkin down at the end of a meal. I usually make her pick it up, but that doesn't discourage her from throwing something else next time.

What am I doing wrong? I'm running out of logical consequences and I'm starting to feel like I can't do anything with her. Help please. 🫩