Is this rude of me ?

So me and my SO , my MIL and her husband went out to eat.

We were talking about how our 2 1/2 yr old is starting headstart soon.

I told my SO the only thing she needs is a small backpack ( since she’s still small and obviously doesn’t need to carry much )

My MIL’s husband insisted on buying it for her and my SO said okay.

So they bought her a cute minnie mouse backpack and it is soooo huge on her. I told my SO it’s too big for her that she won’t be able to carry that. So I told him I’m going to buy her a new one and just use that one for something else.

He said that we should’ve never told him to buy it then... Like umm I’m not the one who said yes 😭

When we tried it on her it literally was right by her knee, she was already struggling.

That’s why I wanted to do all the shopping lol