It doesn’t matter what device or OS you use as the interface is the same across the board. Other behaviors could get the same result so it can be dangerous to jump to conclusions with little evidence. That could throw up all kinds of social awkwardness so it’s more of a quiet process like it is on Instagram or Snapchat. And finally, it’s independently certified no-logs policy means that you can rest assured that there’s no record anywhere of your browsing habits. Find the contact you want to unblock from the list. Thus the most straightforward and simple way is to check their profile images or account status.