Google has made a minor update to the meta tags and attributes that Google supports help documentation and added the two tags Google does not support. Those include the meta keywords tag and HTML tag lang attributes.
Here is the section Google added at the bottom of this page:
Google also made some minor content tweaks to the other parts of this page, so if you want to compare the old version to the new version of that support document.
Nice find Dave Smart - who posted about this on Mastodon and said "The google support docs for Supported meta tags has been updated, like the addition of a 'not supported' section."
I should note, this is not new, Google has not supported these two tags for almost forever - but it is now added to these docs.
Forum discussion at Mastodon.