Twitter has announced a major move to give users more confidence in follower counts:
Over the years, we’ve locked accounts when we detected sudden changes in account behaviour. In these situations, we reach out to the owners of the accounts and unless they validate the account and reset their passwords, we keep them locked with no ability to log in. This week, we’ll be removing these locked accounts from follower counts across profiles globally. As a result, the number of followers displayed on many profiles may go down.
Most people will see a change of four followers or fewer; others with larger follower counts will experience a more significant drop. We understand this may be hard for some, but we believe accuracy and transparency make Twitter a more trusted service for public conversation.
Though the most significant changes are happening in the next few days, follower counts may continue to change more regularly as part of our ongoing work to proactively identify and challenge problematic accounts.