The only GMP requirement is that packaging and processing equipment do not add to, react with, or take from the product. How that happens is up to you. Each product is unique. I’ve had a product which Stainless reacted with the product, and so we had to go to plastic. I’ve had other products where the product would absorb into the plastic, and had to go to stainless.
Here is a FDA published discussion on that.
So you might have to do a material compatability study to determine if plastic is OK. THis can be done via literature search, contacting the supplier of the material you are weighing, or a laboratory study. Also there are a variety of plastics. PVC, PTFE, etc. I suspect that a liquid would have more adsorobtion issues than a powder, but you’ll have to confirm for yourself.