X is changing the way blocking works. On Thursday, the company's Engineering account explained the changes as follows: "If a user who has blocked you replies to one of your posts, you will now be able to see their reply. This change enables you to identify and report any potential bad content that you previously could not view, safeguarding both your account and the overall integrity of our platform."
¯\(°_o)/¯
If they block YOU they can still see your account but you cannot see them.You haven't blocked them
Blocking on twitter has always been one way not two way like here