How do i convince my mom from shopping on shein?

Hello! I think by the title of this you already can tell what this is about but I'll explain some more in here.

Ever since my sister showed my mom shein a few years ago, my mom has been using it ever since, especially when it comes to back to school shopping. I don't like shein because of the amount of information about it and I want to begin exploring alternative j-fashion. Anyways, my mom buys from shein because it's cheaper because we don't have much money and we can get much for the cheap prices.

I want to try to convince her that shein is not a good place to buy from and it's better getting two things from the mall then multiple items from shein but I don't know how to convince her without trying to upset her about the costs and trying to come off as ungrateful.