curl -I "https://en.wikipedia.org/w/api.php?action=visualeditor&mobileformat=html&format=json&paction=parse&formatversion=2&page=MediaWiki%3ASidebar"
HTTP/2 200 
date: Tue, 05 Mar 2024 16:06:15 GMT
server: mw1426.eqiad.wmnet
x-content-type-options: nosniff
mediawiki-api-error: rest-permission-error

We get an API error, where we should not IMO (all other HTML rendering API do work properly) and this seems to be a regression as I believe this was still working a few months ago.

This sounds a bit of a silly operation, but actually - with MWoffliner = we use the "Mediawiki:Sidebar" as example article to check if an API works well!