Explain the problem.

Converting the following:

pandoc -f gfm -t asciidoctor <<EOF
- [ ] a
- [x] b
EOF

produces:

* ☐ a
* ☒ b

instead of using the checklist syntax (see asciidoctor docs):

* [ ] a
* [x] b

This seems related to the recently fixed org-mode reader/writer support for a similar feature.

Pandoc version?

pandoc 2.14.0.3, NixOS