Is my sister screwing with me?

My sister keeps telling me that she can see everything I comment on TikTok, not just on my own posts, but on every random TikTok that I comment on. I don't know if she's just messing with me or if this is really true. Earlier, I commented on a completely random video that showed up on my For You page, and she commented on it too. I was weirded out by this because I thought the chances of that happening were extremely low. She keeps telling me she can see everything, and even if I unfollow her, she can still see everything because I'm in her contacts. Is she messing with me or not? If so, how do I make her or anyone stop seeing what I comment? I don't want anyone to see what I comment on TikTok.