Yes, I have this with my dd, too, sometimes, Washerwoman. I think it's very normal for a stressed out young mum to get grumpy and lash out at the "safest" person, her own mum. And if you're doing a lot of childcare for her, then there's more chance for friction, and so forth.
I think you're very wise to just walk away or fall silent. I do that, too, when it happens because I find words just escalate things.
I'm sure I lashed out at my own dear mum, sometimes, years ago. How I wish I could take it all back, but I know she understood. She did the same to her mum, I saw it as a child. But we all loved each other as dd and I do.
Lottage, Idk what happened to your post. Maybe too long? Anyhow, your situation seems to be about more than a grumpy daughter. She has committed physical and emotional abuse against you. I would stay away, gc or not.