Mismatched engagement
Humans are highly predictable and will, therefore, demonstrate a similar engagement pattern. All Instagram accounts have a unique engagement pattern; acquiring a list of fake followers may cause an account not stop matching the expected engagement rates. An account with fake followers will generally display a noticeably different engagement average than usual as fake followers will generally not engage in any way, bringing down the engagement rate. An account with 100,000 followers but only 100 actively engaging can raise concerns from the intended audience. Some fake followers might notice the engagement problem and start using bots that make meaningless, fake comments to boost the engagement levels, thus scaring off legitimate followers.