I just bought a new thing of cornstarch and every time I try to add it to anything liquid, it just starts fizzing and bubbling up dramatically!

I’m a noob, but I have a general understanding of the basics…

Or at least I think I do?

It fizzles similarly to how baking soda does when you add vinegar to it.

It’s lead to two spillovers in the three times I’ve used it. I’ve used cornstarch before — I’m not unfamiliar with it. But I’ve never seen it do anything like this before…

I’m starting to feel like I’m going crazy.

Anyone have any idea what’s happening?

Ps. I usually buy name brand cornstarch, but they were out so I grabbed a generic brand instead. I immediately emptied out the bag it was in into the airtight container I keep my cornstarch in, so I can’t double check the packaging at this point…

I’m starting to question If I grabbed something else by mistake??

Does anyone have any suggestions on how to confirm if the white powder in my jar is or is not, in fact, cornstarch?