Instagram are adding ‘suggested’ posts to the end of your feed. Once you’re all caught up with posts from your friends, you will now see posts that Instagram thinks you’ll like. 

Suggested posts are based on the accounts you follow, Instagram then shows you posts and accounts like those. You can click the three little dots to let Instagram know if you aren’t interested in a suggested post. 

You won’t be able to opt out of suggested posts but when you see the ‘you’ve reached the end’ banner, you will be able to tap to view older posts instead.