This one says "encrypted by server"
It was created from a terminal with curl, and that changes one thing worth knowing.
What the badge means
Our server generated the key and did the encrypting, because curl cannot run our code. It stored the ciphertext, handed the sender the link, and forgot the key.
Why it is labelled
Every other path encrypts on the sender's device, where we never see the content. This one does not, so we say so - on the page, in the receipts, and in the response headers.
Still stuck? Contact support, or send a secret of your own.