Checks start a history on this installation. Observation time is not Microsoft's edit time, and edits made before collection or reverted between checks are unknown. History is limited to 20 source revisions per page.
Where a page's source is in a public Microsoft documentation repository on GitHub, its page also lists Microsoft's commits, and a change shows Microsoft's newest commit message between the two checks. That commit is the likeliest explanation, not a confirmed one: several commits can land between checks, shared include files change pages too, and commit dates are when the source changed, which can precede publication.
Where Microsoft publishes a page's source under an open license (CC BY 4.0, or MIT for Entra), a change shows the changed passages in Microsoft's wording, with removed and added words marked. Other pages show short quotes of the changed words only. Full document copies are not published here.