That image is found in the link I shared, with additional detail :)
Re:HTTPS Explained with Carrier Pigeons
by jagged-chisel on Monday January 02, 2023 @04:24PM
(#34223869)
I sourced it from your link. I disagree that the above commenter is describing "PKI" and is specifically describing "DH Key Exchange" as evidenced by the image linked from the article you referenced.
https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Pu...