Keep in mind the activity feed shows activity of the >7500 or so accounts you are following, it's the same information sorted differently that you see in your main feed of followings, the one you view by the home icon.
The users who are followng you among other accounts normally want to be able to see the activity of the accounts they are following, either ranked by IG's algorithm through the home icon or sorted in reverse chronological order (most recent at the top) in the following tab viewed under the heart icon that you referred to.
There's no technique to avoid likes and follows showing up in the activity track / feed of accounts that are following you -- they're following you because they want to be able to see that information -- but if you are doing follow/unfollows/likes on accounts that are of interest to accounts who are following you the activity may not be seen as especially annoying. It may also be more likely to be seen as similar of other accounts they are following.
If it still is a concern for you, you might schedule your likes and follows to be done during hours when your followers are less active, and just do posting during or before their most active hours. They'll still see app notifications of likes and follows done since their last access to the IG app regardless of the time you do your likes and follows.