Go re-watch the video from 19mins to 20mins again.
DF say that it running lesser quality in 120fps mode, "pays off".
That means not a bug (but a choice, to mantain 120fps more consistantly), john says that in the video dude.
They say 2 differnt things, about the same issue (at differnt times in the video).
Digital foundry said it was likely a bug.
I would assume the Playstation 5 was supposed to take a visual hit in that mode and didn't... And will likely be rectified at a later date.
The Playstation 5 also has another bug which impacts the dynamic range... Hopefully that gets fixed as well.
Yeah they mentioned a SDR bug, on the PS5, so if your TV does support HDR, it looks darker than its supposed too (and can crush blacks, in dark area's of the game) (even if your trying to compensate by turning up brightness or such). Hopefully that gets fixed.
John also lateron says, that the lesser graphic on the xsx 120 fps mode, is paying off in certain tracks/times, and the trade off was worth it.
That to me, atleast doesnt sound that much like a bug. Its 19mins+ into the video.