The simplest answer to are Instagram Polls Anonymous is no they are not.
Every time you submit an answer to an Instagram Poll the creator of the poll will get a notification telling them who answered the poll along with your answer. Instagram also gives the creator of the poll the option to share your answer and they can go as far as tagging you with the answer share.
I love to use polls to engage my audience, get feedback, and as a way to repurpose images. I use it most frequently on my podcast page for Colin’s Conversations to get people’s opinions on guests.