Someone has blocked you on Snapchat if you observe these signs:

• You cannot find their username or profile when searching in Snapchat.
• Previous conversations with them disappear from your chat list.
• They no longer appear in your Friends List.
• You cannot see their Bitmoji, Snap Score, or Stories.
• Messages or snaps you send remain "Pending" and are never delivered.

To confirm if you have been blocked, you can try searching for their username using another Snapchat account. If their profile appears there but not on your main account, it's a strong indication that you have been blocked. Also, if you cannot see their Snap Score or profile details, it likely means they blocked you.

In short, the main signs revolve around disappeared profiles, vanished chats, no message delivery, and missing Snap Score or Bitmoji from the user on your Snapchat.