My sister does this. A lot.
We went for dinner and when I politely asked about it (I responded to something she was saying and looked affronted, and replied “can I finish please?”) to which I reminded her that it was a conversation, not a lecture/monologue... she very firmly replied that no she wasn’t monologuing, but nevertheless carried on and in.
Sadly I think our relationship is pretty non existent anyway (or at least headed that way) - she has a rigidity of thinking where she just won’t accept or tolerate other people’s different opinions.
Anyone have any advice?