Check your followers list and compare it to a previous list or screenshot
Search the person’s username in your followers list
Visit their profile and see whether you still follow each other
Use Instagram’s “Following” and “Followers” lists to manually compare changes over time
Review recent notifications if you noticed a sudden change
Use a third-party follower-tracking app only if you trust it and understand the privacy risks
Keep in mind Instagram does not provide a built-in feature that shows exactly who unfollowed you