Just what agreements exist between the Kurds and the Russians for the Russians to betray?
If there are none, the Russians should consider Russian interests first, then Syrian interests by treaty.
Fake news propaganda promoting a Fake requirement that Russia should watch out for the Kurds, as opposed to the US, who, of course, don't have to meet that requirement.
They have tried to court Kurd loyalties and friendship.
I never take Russian statement at face value. But yes, they have their own agenda.
There is a lot of speculation of what Russia’s actual reasons for supporting the “agreement”. But like Mattis said (and I said here before him): “the devil is in the details” of the agreement.