I had it on pretty good authority that its only being transmitted to spark at 50fps and spark are upscaling it before sending it out... god knows where they are pulling 10fps from.
In conversation its often stated as 30/60. But if its 25/50 content its sent as that.
As far as I'm aware all the RWC content is actually 50.
Maybe that's why game play looks jittery at 60hz on the ATV4k, but fine at 50hz