Twitter Changes How Blocking Users Works
If your account is public, blocking a user does not prevent that user from following you, interacting with your Tweets, or receiving your updates in their timeline. If your Tweets are protected, blocking the user will cause them to unfollow you.
Not only does this policy change make no sense (it effectively nullifies what it means to block someone) but I don’t see how this helps Twitter either. It’s just a stupid move for both the company and users.