You can no longer find their username in Snapchat search
Their chat disappears from your chat list
You cannot view their Snap Score or profile details
Your snaps and messages to them stay pending
Their stories no longer appear for you
You cannot add them as a friend
Their profile may show as unavailable or not found
You may still see old chats, but not their current profile
If you use another account and can find them, you were likely blocked