Does it show that you have?
Or is it only a notification when you do block them?
I was just curious.
Yes it does, because there is one person who's done it to me like 50 times. You get an event saying you were removed from their block list, even if you have them blocked.
If you think the person is doing that to harass you, you can submit a ticket and let staff know. Repeatedly blocking and un-blocking a person like that is a form of harassment, and site staff can put an end to it.
