Contact
Pandoc is a volunteer project, not a company: there's no support desk and no contact form. There are four public places instead, and which one you want depends on what you're asking.
Ask on pandoc-discuss, the project's mailing list, or in GitHub Discussions. Both are read by people who know pandoc well, and both are public, so the answer helps whoever searches for it next.
Worth searching before you ask — it's long, but it usually has the answer already: the manual
Report it on the issue tracker. A conversion that produces the wrong output is a bug worth filing even if you're not sure — include the input, the command you ran and the version from pandoc --version.
Pandoc is free software under the GPL, written in Haskell, and takes contributions through pull requests. The contributing guide covers the build, the tests and what makes a change likely to be accepted.
Pandoc is maintained by John MacFarlane, a philosophy professor at Berkeley, who has been at it since 2006 alongside hundreds of contributors. His own site is the right place for anything about him rather than about pandoc.
This site isn't run by the pandoc project and can't answer for it. If something here is wrong, the project's own pages are the authority: pandoc.org.