A lot of them are also not very happy with how quickly she is growing up.
Over the weekend, Millie posted a gorgeous set of photos of herself on Instagram, wearing a skintight snakeskin dress. She looked absolutely beautiful, but it was definitely a more mature look for her.
Deciding to have a bit of fun with it, Millie asked her fans to come up with a caption for her.
However, fans instead criticised her outfit.
Of course, Millie saw the negative comments and decided to respond to them with a sassy AF comment. Posting a cute selfie to her Instagram story, she wrote, "ik everyone on my last pic wants me to 'act my age' but quite frankly its my instagram and if i choose to post that picture and you dont like it... scroll past it."
That's when ex-boyfriend Jacob Sartorius swooped in, to ~save the day~
"stunning," he posted on the picture.