My mother is 96 with dementia. She talks non-stop, using baby talk. Anyone else experiencing this?

Sadly, that can be normal at some stages of dementia. She isn't aware of what she is doing or saying... just reverting back to what she did as a little girl.
She may be able to respond at times, then other times not. Hard to watch for you. She is not 'herself'. Other times, it may be attention seeking.
Is she in a place of care? What meds is she on?

I don't get baby talk. I get mocking.

There are some patients in MC who have dolls. Do you think that might help? Or make worse?