I only know about Cryptotalk. It's a campaign that was run by Yobit before.
This part of your answer is irrelevant too.
Cryptotalk runs its signature campaign in Bitcointalk through Yobit team, it is correct but, a big but, it was hosted in a last bear market, in 2019. I am sure you are here long enough to know Bitcointalk had signature campaigns years before 2019.
CryptoTalk.Org Signature Campaign [Yobit Panel].
It was the answer to OP's question.
So, apart from here in bitcointalk, has any other forum or website adopted the signature campaign system of advertisement?
Does theymos have a patent for signature campaign such that no other forum can replicate what is happening here without his permission.
I only know about Cryptotalk. It's a campaign that was run by Yobit before.
And you also see the reply when a member ask if he could run a signature campaign in cryptotalk forum.
https://cryptotalk.org/topic/367150-signature-campaign/https://cryptotalk.org/topic/363807-%F0%9F%9F%A5bounty%F0%9F%9F%A5-solarblox-crypto-solar-mining-250-000-sbx-escrow-%F0%9F%A4%91-signature/ ( their bounty section I guess).
So, what happened at that time was that Cryptotalk ran a signature campaign on Bitcointalk to promote their website. They also had a signature campaign on their own website.