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I understand that but I never understood why a bunch of people follow me and then unfollow me it’s like some kind of game.

It's a follow phishing technique, people usually follow back so they follow a bunch of people to get follows back then they unfollow them all and add new people.

I used to have the Instagram unfollow app. It allowed me to unfollowed those who unfollowed me without searching to see who unfollowed me.