I was searching for an old post of mine in the PDF language and specification but it seems that all subforums are gone.
(Or did you move all the discussions regarding the pdf specification somewhere?)
It it is gone that would be quite bad! And also people now don't know where to post anymore since there is no general PDF section. There is the 'acrobat' forum but this is a product which has "nothing" to do with the pdf language specification...
Anything older than 2016 is gone.
That is unfortunate.
But where are the posts younger than 2016? To which forum have they been moved?
Yes, the former JIVE system had sub-forums for SDK, accessibility, scripting, etc... This new Khoros system is flat but tagged. I would expect post-2016 PDF content to be in Acrobat under the Standards and Accessibility tag. See screenshot.
The wealth of knowledge posted before 2016 is no longer available and this site search is not usable IMO. Search using Google search you may be able to find your old post it its still available. If not the links Google finds will be redirected to Adobe Support Community.