My account is 4mos, decent engagement, 50 or so posts.
I unfollowed 1000+ per day several days in a row, no issues using FL
IG seems unfollow / follow as "Relationship" , then rates are based on public, private API's and manual
Public API max is 60 relationships per hour, so if you're following unfollowing you can do both, as long as you don't exceed 60 per hour.
Private API (Followliker) the rates are a little higher, same rule applies thoguh
So when I unfollowed 1000+ , I did not run a follow routine. I could follow 500 / unfollow 500 though..