How do you know who follows and unfollows you on Twitter?

"Unfortunately, Twitter doesn't provide a built-in feature to see who follows and unfollows you, but there are third-party apps and websites that can track your followers' activity.

There is a notification that who followed you but there is no way to who unfollowed you if you have a huge list of followers.

Tracking followers is easy on Twitter, but tracking unfollowers isn’t. Because Twitter doesn’t provide any data for tracking unfollowers. That’s why I use the tool FollowersAudit. FollowerAudit is a Twitter followers and unfollowers tracking tool, which can provide you these stats for your as well as any other public Twitter account. You will get a list of all the followers and unfollowers.

Twitter doesn't provide this data thus we need to use thirdparty tools like unfollowerstats.com

As of my last knowledge update in September 2021, Twitter does not offer a direct way to track who follows and unfollows you, but you can use external tools or services that provide such insights.