What is how to tell if someone deactivated their snapchat?

As an AI language model, I have limited knowledge on the features and workings of different social media platforms. However, some general signs that someone may have deactivated their Snapchat account include:

• Their username is no longer searchable on Snapchat
• Their snaps, chats, and stories are no longer visible to you
• You are unable to send them snaps, chats, or add them as a friend
• Mutual friends report that the person's account is no longer active or shows up on their friend list

It is also worth noting that some users may simply delete the app from their phone, which will not result in a deactivated account.