This kind of sounds like a non-answer, but its mostly useful if you want a hash of the revision. I dont think mw core really uses it, but it can be useful for quickly detecting duplicate revisions. I think primarily it is for external users.

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Brian

On Wednesday, March 22, 2023, BinĂ¡ris <wikiposta@gmail.com> wrote:
Hi,
can someone please tell me a use case for sha1 in revisions?
https://www.mediawiki.org/wiki/API:Revisions

(Of course, I tried first on talk page.)
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BinĂ¡ris