Yaroslav Schekin (ysch) reported on irc that Index Scans Backward do not display properly.
After checking I found out that if explain is in JSON/YAML/XML – node type is changed to “Index Scan" (or “Index Only Scan" if it was originally “Index Only Scan Backward").
Some more debugging/diagnosing later and I found the problem.
Basically, in case of backward scans, non-text formats store base type (“Index Scan" / “Index Only Scan") in “Node Type", and the direction is saved as another part of structure: “Scan Direction".
There were no changes in explain.depesz.com code itself, so it just works.
If you'd like to see it:
Sorry for the bug, and thanks Yaroslav for the report.