T147544 introduced $wgPageTriageNoIndexUnreviewedNewArticles at https://www.mediawiki.org/wiki/Extension:PageTriage#Extension_configuration
When enabled like at enwiki, it adds noindex to new articles for 30 days, unless the page is reviewed.
But action=info ("Page information") for the page says "Indexing by robots Allowed" even though the html source says:
<meta name="robots" content="noindex,nofollow"/>

action=info should say "Indexing by robots Disallowed" until noindex is removed.
Maybe there should also be an indication why indexing is disallowed, or it could say "Temporarily disallowed".
This was discussed at https://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=780078928#Article_not_indexing_in_Google_despite_everything_in_order

Examples are temporary but new examples can be found by picking an article at https://en.wikipedia.org/wiki/Special:NewPages and clicking "Page information".
I currently see it at https://en.wikipedia.org/w/index.php?title=Black_Origami&action=info