Back in February when I wrote my previous blog on this topic, you could turn off News & Interests via a per-user registry edit. At that point, it was just in an Insider build, but it’s now coming soon — and not just in the “next” Windows 10 release but to existing ones as well (1909 and later). See the announcement for more detail.
There was some good news in that announcement: There is now a Group Policy for turning this off at the machine level, at Computer Configuration > Administrative Templates > Windows Components > News and interests > Enable news and interests on the taskbar.
Until a new set of ADMX files is released, you can pull the ADMX and ADML files from an Insider build (they are present on build 21359, C:WindowsPolicyDefinitionsFeeds.admx and C:WindowsPolicyDefinitions<language>Feeds.adml) and use those to update your group policy central store or local policy files.
To disable this in your unattend.xml (effectively setting the GPO directly), you can include something like this in your unattend.xml:
The same announcement implies that there is an MDM policy available, but as the referenced page hasn’t yet been updated to include this new setting, it’s not clear if this is a native MDM policy or an ADMX-backed policy. But either way works.