.

تبدو وكأنها نكتة متداولة لفترة طويلة / مزحة متداولة لفترة طويلة

It would be, which is why the idea of the simulation hypothesis has been a long-running, sort-of joke
(1)
وهذا هو السبب الذي جعل فكرة فرضية المحاكاة تبدو كمزحة متداولة لفترة طويلة
(2)

وهذا هو السبب الذي جعل فكرة فرضية المحاكاة تبدو كمزحة في التداول لفترة طويلة

(3)

وهذا هو السبب الذي جعل فكرة فرضية المحاكاة تبدو كنكتة في التداول لفترة طويلة

نكتة او اصحوكة

English term (edited): sort-of

Your question consists of two separate terms, "long-standing" and "sort-of," which should have been posted as two questions.

The first term, "long-standing" has been admirably addressed by the answers that preceded mine. I will address the term "sort-of."

"Sort-of" is a term we throw in when we are not sure if the expression we are using adequately describes what we have in mind. It is a somewhat apologetic expression to tell the reader or listener something like "I know that my words are not precise enough, but you know what I mean." It is like saying, "I am not very good with words, but I hope I am making some sense." or "I am having difficulty putting my concepts in precise terms because the concept is hard to capture, but I think you know what I am trying to say," and so on.